High blocking temperature spin orbit torque electrode

ABSTRACT

An apparatus is provided which comprises: a magnetic junction having a magnet with a first magnetization; an interconnect adjacent to the magnetic junction, wherein the interconnect comprises an antiferromagnetic (AFM) material which is doped with a doping material (Pt, Ni, Co, or Cr) and a structure adjacent to the interconnect such that the magnetic junction and the structure are on opposite surfaces of the interconnect, wherein the structure comprises a magnet with a second magnetization substantially different from the first magnetization.

BACKGROUND

Embedded memory with state retention can enable energy and computationalefficiency. However, leading spintronic memory options, for example,spin transfer torque based magnetic random access memory (STT-MRAM),suffer from the problem of high voltage and high write current duringthe programming (e.g., writing) of a bit-cell. For instance, large writecurrent (e.g., greater than 100 μA) and voltage (e.g., greater than 0.7V) are required to write a tunnel junction based magnetic tunneljunction (MTJ). Limited write current also leads to high write errorrates or slow switching times (e.g., exceeding 20 ns) in MTJ based MRAM.The presence of a large current flowing through a tunnel barrier leadsto reliability issues in magnetic tunnel junctions.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the disclosure will be understood more fully from thedetailed description given below and from the accompanying drawings ofvarious embodiments of the disclosure, which, however, should not betaken to limit the disclosure to the specific embodiments, but are forexplanation and understanding only.

FIG. 1A illustrates a magnetization response to an applied magneticfield for a ferromagnet.

FIG. 1B illustrates a magnetization response to an applied magneticfield for a paramagnet.

FIGS. 2A-B illustrate a three-dimensional (3D) view and correspondingtop view, respectively, of a device having an in-plane magnetic tunneljunction (MTJ) stack coupled to a spin orbit coupling (SOC)interconnect.

FIG. 2C illustrates a cross-section of the SOC interconnect withelectrons having their spins polarized in-plane and deflected up anddown resulting from a flow of charge current.

FIGS. 3A-B illustrate a 3D view and corresponding top view,respectively, of a device having an in-plane MTJ stack coupled to a SOCinterconnect, where the in-plane magnetization is co-linear with adirection of current.

FIGS. 4A-B illustrate a 3D view and corresponding top view,respectively, of a device having an out-of-plane MTJ stack coupled to aSOC interconnect.

FIGS. 5A-C illustrate a mechanism for switching an out-of-plane MTJmemory device (e.g. device of FIG. 4A) formed on a spin orbit torqueelectrode.

FIG. 5D illustrates a cross-section of the out-of-plane MTJ memorydevice (e.g. device of FIG. 4A) with spin directions in an interconnectof the device when temperature (T) is below blocking temperature(T_(blocking)).

FIG. 5E illustrates a cross-section of the out-of-plane MTJ memorydevice (e.g. device of FIG. 4A) with spin directions in an interconnectof the device when temperature (T) is above blocking temperature(T_(blocking)).

FIG. 6A illustrates a plot showing write energy-delay conditions for onetransistor and one MTJ with spin Hall effect (SHE) material (e.g.,device of FIGS. 2-3) compared to traditional MTJs.

FIG. 6B illustrates a plot comparing reliable write times for spin HallMRAM and spin torque MRAM.

FIG. 6C illustrates a plot showing remnant pinning field curve for a topspin valve pinned by 200 A of PtMn.

FIG. 6D illustrates a plot showing unblocked ratio in spin-valvestructures with the different antiferromagnetic biasing layers.

FIG. 6E illustrates a plot showing blocking temperature distribution inthe corresponding structures.

FIGS. 7A-B illustrate a 3D view and corresponding cross-section view,respectively, of a device having a magnetic junction with magnets havingperpendicular magnetizations, and a doped spin orbit torque(SOT)/antiferromagnetic (AFM) interconnect, according to someembodiments of the disclosure.

FIGS. 7C-D illustrate a 3D view and corresponding cross-section view,respectively, of a device having a magnetic junction with magnets havingperpendicular magnetizations, and a composite interconnect having AFMmaterial, according to some embodiments of the disclosure.

FIGS. 7E-F illustrate a 3D view and corresponding cross-section view,respectively, of a device having a magnetic junction with magnets havingperpendicular magnetizations, and doped SOT/AFM interconnect, and a viacomprising an in-plane magnet adjacent to the SOT/AFM interconnect,according to some embodiments of the disclosure.

FIGS. 7G-H illustrate a 3D view and corresponding cross-section view,respectively, of a device having a magnetic junction with magnets havingperpendicular magnetizations, and the SOT/AFM interconnect, and a viacomprising an in-plane magnet and an AFM one of which is adjacent to theSOT/AFM interconnect, according to some embodiments of the disclosure.

FIG. 7I-J illustrate a 3D view and corresponding cross-section view,respectively, of a device having a magnetic junction with magnets havingperpendicular magnetizations, where an AFM is embedded in the dopedSOT/AFM interconnect, and a via comprising an in-plane magnet which isadjacent to the AFM, according to some embodiments of the disclosure.

FIG. 8A illustrates a cross-section of a device having a magneticjunction with magnets having perpendicular magnetizations, where a freemagnet structure of the magnetic junction comprises a stack of magnetswith perpendicular magnetizations, and a via comprising an in-planemagnet and/or an AFM one of which is adjacent to the SOT/AFMinterconnect with higher blocking temperature, according to someembodiments of the disclosure.

FIG. 8B illustrates a cross-section of a device having a magneticjunction with magnets having perpendicular magnetizations, where a freemagnet structure and a fixed magnet structure of the magnetic junctioncomprises a stack of magnets with perpendicular magnetizations, and avia comprising an in-plane magnet and/or an AFM, one of which isadjacent to the SOT/AFM interconnect with higher blocking temperature,according to some embodiments of the disclosure.

FIG. 8C illustrates a cross-section of a device having a magneticjunction with magnets having perpendicular magnetizations, where a fixedmagnet structure and one of the free magnets of a free magnet structureof the magnetic junction comprises a stack of magnets with perpendicularmagnetizations, and a via comprising an in-plane magnet and/or an AFM,one of which is adjacent to the SOT/AFM interconnect with higherblocking temperature, according to some embodiments of the disclosure.

FIG. 8D illustrates a cross-section of a device having a magneticjunction with magnets having perpendicular magnetizations, where a fixedmagnet structure of the magnetic junction comprises a stack of magnetswith perpendicular magnetizations, and a via comprising an in-planemagnet and/or an AFM, one of which is adjacent to the SOT/AFMinterconnect with higher blocking temperature, according to someembodiments of the disclosure.

FIG. 8E illustrates a cross-section of a device having a magneticjunction with magnets having perpendicular magnetizations, where a fixedmagnet structure and one of the free magnets of a free magnet structureof the magnetic junction comprises a stack of magnets with perpendicularmagnetizations, and a via comprising an in-plane magnet and/or an AFM,one of which is adjacent to the SOT/AFM interconnect with higherblocking temperature, according to some embodiments of the disclosure.

FIG. 8F illustrates a cross-section of a device having a magneticjunction with magnets having perpendicular magnetizations, where a freemagnet structure and a fixed magnet structure of the magnetic junctioncomprises a stack of magnets with perpendicular magnetizations, and avia comprising an in-plane magnet which is adjacent to an AFM embeddedin the SOT/AFM interconnect with higher blocking temperature, accordingto some embodiments of the disclosure.

FIG. 9A illustrates a plot showing spin polarization capturing switchingof a free magnet structure which is exchanged coupled or biased by amagnetic via under an SOT/AFM interconnect with higher blockingtemperature, according to some embodiments of the disclosure.

FIG. 9B illustrates a magnetization plot associated with FIG. 9A,according to some embodiments of the disclosure.

FIG. 9C illustrates a plot showing spin polarization capturing switchingof the free magnet structure which is exchanged coupled or biased by amagnetic via under an SOT/AFM interconnect with higher blockingtemperature, according to some embodiments of the disclosure.

FIG. 9D illustrates a magnetization plot associated with FIG. 9C,according to some embodiments of the disclosure.

FIGS. 10A-C illustrate a cross-sectional view of a SOT memory device(e.g., any one of devices of FIGS. 7-8) coupled to a first transistorand a bit line, according to some embodiments.

FIG. 11 illustrates a flowchart of a method for forming a device ofFIGS. 7-8, in accordance with some embodiments.

FIG. 12 illustrates a smart device or a computer system or a SoC(System-on-Chip) with a magnetic junction based memory having a via fordipole and exchange coupling in the SOT/AFM interconnect with higherblocking temperature, according to some embodiments of the disclosure.

DETAILED DESCRIPTION

Perpendicular Spin Orbit Torque (PSOT) MRAM uses spin orbit torque(SOT), also referred to as Spin Orbit Coupling (SOC), from heavy metal,two-dimensional (2D) material, Antiferromagnets (AFM), or topologicalinsulator(s) (TI) to switch the perpendicular magnet coupled to an SOTelectrode. Typically, in-plane magnetic field through the SOT electrodeis used for deterministic bidirectional switching of the free magnet ofthe PSOT MRAM. This in-plane magnetic field can be generated by AFMmaterials as SOT electrode or magnetically doped heavy metal electrodeor magnetic via or by designing a complex free magnet layer stack.

Antiferromagnetic materials such as triangular, chiral, hexagonal,kagomi, and/or cubic show a huge promise for being used as an SOTelectrode layer in PSOT devices. AFM materials have large spin orbittorques and can apply in-plane bias magnetic field to the free magnetlayer of the PSOT device using the interfacial exchange bias effect. Thein-plane magnetic field from the exchange bias is one of the ways bywhich symmetry can be broken for achieving repeatable and deterministicbidirectional switching of the PSOT MRAM.

One challenge in using AFM materials directly in the SOT electrode isthat AFM materials typically have low blocking temperature. The term“blocking temperature” here generally refers to a temperature belowwhich the AFM material loses its magnetic orientation. Blockingtemperature is dependent on the thickness and the grain size ofantiferromagnetic materials. If the AFM is deposited along oneorientation (e.g., x-direction) by annealing and field cooling, then dueto passing of electric current through the SOT/AFM electrode, the AFM ofthe SOT/AFM electrode can be heated above its blocking temperature andwill get re-magnetized depending upon the direction of the magneticfield it senses. This will affect the reliability of the SOT/AFM MRAMoperation.

One way to solve the above problem is by changing the thickness of theantiferromagnetic material, in accordance with some embodiments. Forexample, by increasing the thickness of the AFM material of the SOT/AFMelectrode, the blocking temperature is increased. Another way to solvethe above problem is to replace the antiferromagnetic materialaltogether with a material which does not have a low blockingtemperature.

One problem with the approach of changing the thickness of theantiferromagnetic material is that for efficient SOT operation, thethickness of the AFM in the SOT/AFM electrode is optimal when it iscomparable to spin diffusion. Hence increasing the thickness of the AFMto achieve the necessary thermal budget may not achieve desirableresults. Further, the problem with approach of replacing the AFMmaterial is that not all the AFM options have large spin orbit torque,so the AFM materials may not be simply completely substituted becausecertain SOT is desired.

Some embodiments describe a spin orbit coupling or spin orbit torque(SOC/SOT) based magnetic memory in which the SOT electrode (e.g.,Graphene, Bi₂Se₃, Bi_(x)Te_(y)Se_(1-x-y), Bi_(x)Sb_(1-x), WSe₂, WTe₂,PtSe₂, PtTe₂, PtTe₂, MoSe₂, MoS₂, or MoTe₂) also includes AFM material(e.g., IrMn) which is doped or co-sputtered with one or more of heavymetals, oxygen, nitrogen, or other AFM materials with high blockingtemperature. For example, the SOT/AFM electrode having IrMn is dopedwith one of: Pt. Ni, Co, or Cr. In some embodiments, the SOT/AFMelectrode is adjacent to an AFM oxide layer (e.g., a Bismuth Ferrite(BFO)). As such, the blocking temperature of the SOT/AFM electrode isrevised than when un-doped or when no AFM oxide layer is used.

In some embodiments, the SOT/AFM electrode of the magnetic memorycomprises multilayers of different AFM materials or multilayers of AFMwith heavy metals. In some embodiments, the thinner AFM layer, among themultilayers, is the one with higher blocking temperature. In someembodiments, the thinner layer, among the multilayers, comprises a heavymetal. In some embodiments, the thicknesses of these multilayers areless than the spin diffusion length of the materials to ensure that thehighest spin orbit torque is achieved. In this example, the higher spinorbit torque layer forms the interface with the free magnet of themagnetic memory (e.g., magnetic tunneling junction or spin valve).

In some embodiments, the magnetic device comprises a perpendicular freemagnet in contact with the SOT/AFM electrode with higher blockingtemperature. In some embodiments, the SOT/AFM electrode is coupled to amagnetic via to produce dipole/exchange bias fields. In someembodiments, the magnetic via comprises an AFM or an in-plane fixedmagnet. In some embodiments, in-plane exchange bias from the AFM and/oran in-plane fixed magnet is used to template the magnetic orientation ofthe free magnets of the magnetic junction. As such, the free magnets ofthe magnetic junction provide a strong effective in-plane magnet effect.

In some embodiments, both an in-plane fixed magnet and an AFM are formedin a via which is coupled to or adjacent to a surface of the SOC/AFMelectrode such that the magnetic junction is formed on the other surfaceof the SOC/AFM electrode. In some embodiments, the in-plane fixed magnetunder the SOC/AFM electrode has a length longer than a length of themagnetic junction. Here, length refers to a distance along a y-axis asdescribed with reference to various figures. In some embodiments, thein-plane magnet is made thick enough so that it is stable. Here,stability generally refers to the permanency of the magnetizationdirection. An unstable magnet in this example would be one that switchesits magnetization upon application of an external field. In someembodiments, the AFM comprises Ir and Mn (or any other AFM) which cantemplate the magnetic orientation of the in-plane magnet in the via.

In some embodiments, the free magnet structure of the magnetic junctioncomprises at least two free magnets that are coupled by a couplinglayer. In some embodiments, the coupling layer comprises one or more of:Ru, Os, Hs, Fe, or other similar transition metals from the platinumgroup of the periodic table. In some embodiments, the coupling layer(s)are removed so that the free magnets of the free magnet structure orstack are directly connected with one another forming a single magnet(or a composite magnet).

In some embodiments, one or more of the free magnets of the free magnetstructure of the magnetic junction comprises a composite magnet. Thecomposite magnet may be a super lattice including a first material and asecond material, wherein the first material includes one of: Co, Ni, Fe,or Heusler alloy, and wherein the second material includes one of: Pt,Pd, Ir, Ru, or Ni. In some embodiments, the fixed magnet of the magneticjunction also comprises a composite magnet.

There are many technical effects of the various embodiments. Forexample, in some embodiments, the out-of-plane magnetization switchingenables perpendicular magnet anisotropy (PMA) based magnetic devices(e.g., MRAM and logic) comprising spin orbit effects that generateperpendicular spin currents. The perpendicular magnet switch of someembodiments enables low programming voltages (or higher current foridentical voltages) enabled by giant spin orbit effects (GSOE) forperpendicular magnetic memory and logic. The perpendicular magnetswitch, of some embodiments, results in lower write error rates whichenable faster MRAM (e.g., write time of less than 10 ns). Theperpendicular magnet switch of some embodiments decouples write and readpaths to enable faster read latencies. The perpendicular magnet switchof some embodiments uses significantly smaller read current through themagnetic junction (e.g., MTJ or spin valve) and provides improvedreliability of the tunneling oxide and MTJs. For example, less than 10μA compared to 100 μA for nominal write is used by the perpendicularmagnet switch of some embodiments.

In some embodiments, one advantage of doping or co-sputtering the lowtemperature high-efficiency SOT/AFM material with heavy metals, oxygen,nitrogen, or other AFM with high blocking temperature is that it willallow for higher current and higher temperature operation without theloss of AFM nature. Doping or co-sputtering with heavier metals willincrease the blocking temperature of the AFM. Typically, heavy metalsare less responsive to diffusion. In some embodiments, doping theSOT/AFM electrode with nitrogen and oxygen has the potential to increasenot just the blocking temperature, but the spin orbit torque generatedby the AFM layer as well. This makes the PSOT based MRAM more reliable.

In some embodiments, using multilayers for the SOT/AFM electrode allowsmore current to flow through the SOT/AFM electrode without the worry ofexceeding the blocking temperature. By engineering the thicknesses ofthe multilayers properly, the SOT efficiency of the layers can beincreased greatly while the heating effect is reduced by reducing theimpedance of the magnetic device. This also makes the PSOT based MRAMmore reliable. In some embodiments, the fixed in-plane magnet and/or theAFM coupled to one surface of the SOT/AFM interconnect provides anadditional effective in-plane field which is used for switching the freemagnet(s) of the free magnet structure or stack (of the magneticjunction) using spin orbit torque effect. As such, faster switching andlower power switching is achieved for the magnet junction. Othertechnical effects will be evident from the various figures andembodiments.

In the following description, numerous details are discussed to providea more thorough explanation of embodiments of the present disclosure. Itwill be apparent, however, to one skilled in the art, that embodimentsof the present disclosure may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form, rather than in detail, in order to avoidobscuring embodiments of the present disclosure.

Note that in the corresponding drawings of the embodiments, signals arerepresented with lines. Some lines may be thicker, to indicate moreconstituent signal paths, and/or have arrows at one or more ends, toindicate primary information flow direction. Such indications are notintended to be limiting. Rather, the lines are used in connection withone or more exemplary embodiments to facilitate easier understanding ofa circuit or a logical unit. Any represented signal, as dictated bydesign needs or preferences, may actually comprise one or more signalsthat may travel in either direction and may be implemented with anysuitable type of signal scheme.

The term “free” or “unfixed” here with reference to a magnet refers to amagnet whose magnetization direction can change along its easy axis uponapplication of an external field or force (e.g., Oersted field, spintorque, etc.). Conversely, the term “fixed” or “pinned” here withreference to a magnet refers to a magnet whose magnetization directionis pinned or fixed along an axis and which may not change due toapplication of an external field (e.g., electrical field, Oersted field,spin torque,).

Here, perpendicularly magnetized magnet (or perpendicular magnet, ormagnet with perpendicular magnetic anisotropy (PMA)) refers to a magnethaving a magnetization which is substantially perpendicular to a planeof the magnet or a device. For example, a magnet with a magnetizationwhich is in a z-direction in a range of 90 (or 270) degrees+/−20 degreesrelative to an x-y plane of a device.

Here, an in-plane magnet refers to a magnet that has magnetization in adirection substantially along the plane of the magnet. For example, amagnet with a magnetization which is in an x or y direction and is in arange of 0 (or 180 degrees)+/−20 degrees relative to an x-y plane of adevice.

The term “device” may generally refer to an apparatus according to thecontext of the usage of that term. For example, a device may refer to astack of layers or structures, a single structure or layer, a connectionof various structures having active and/or passive elements, etc.Generally, a device is a three-dimensional structure with a plane alongthe x-y direction and a height along the z direction of an x-y-zCartesian coordinate system. The plane of the device may also be theplane of an apparatus which comprises the device.

Throughout the specification, and in the claims, the term “connected”means a direct connection, such as electrical, mechanical, or magneticconnection between the things that are connected, without anyintermediary devices.

The term “coupled” means a direct or indirect connection, such as adirect electrical, mechanical, or magnetic connection between the thingsthat are connected or an indirect connection, through one or morepassive or active intermediary devices.

The term “adjacent” here generally refers to a position of a thing beingnext to (e.g., immediately next to or close to with one or more thingsbetween them) or adjoining another thing (e.g., abutting it).

The term “circuit” or “module” may refer to one or more passive and/oractive components that are arranged to cooperate with one another toprovide a desired function.

The term “signal” may refer to at least one current signal, voltagesignal, magnetic signal, or data/clock signal. The meaning of “a,” “an,”and “the” include plural references. The meaning of “in” includes “in”and “on.”

The term “scaling” generally refers to converting a design (schematicand layout) from one process technology to another process technologyand subsequently being reduced in layout area. The term “scaling”generally also refers to downsizing layout and devices within the sametechnology node. The term “scaling” may also refer to adjusting (e.g.,slowing down or speeding up—i.e. scaling down, or scaling uprespectively) of a signal frequency relative to another parameter, forexample, power supply level.

The terms “substantially,” “close,” “approximately,” “near,” and“about,” generally refer to being within +/−10% of a target value. Forexample, unless otherwise specified in the explicit context of theiruse, the terms “substantially equal,” “about equal” and “approximatelyequal” mean that there is no more than incidental variation betweenamong things so described. In the art, such variation is typically nomore than +/−10% of a predetermined target value.

Unless otherwise specified the use of the ordinal adjectives “first,”“second,” and “third,” etc., to describe a common object, merelyindicate that different instances of like objects are being referred to,and are not intended to imply that the objects so described must be in agiven sequence, either temporally, spatially, in ranking or in any othermanner.

For the purposes of the present disclosure, phrases “A and/or B” and “Aor B” mean (A), (B), or (A and B). For the purposes of the presentdisclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B),(A and C), (B and C), or (A, B and C).

The terms “left,” “right,” “front,” “back,” “toP,” “bottom,” “over,”“under,” and the like in the description and in the claims, if any, areused for descriptive purposes and not necessarily for describingpermanent relative positions. For example, the terms “over,” “under,”“front side,” “back side,” “top,” “bottom,” “over,” “under,” and “on” asused herein refer to a relative position of one component, structure, ormaterial with respect to other referenced components, structures ormaterials within a device, where such physical relationships arenoteworthy. These terms are employed herein for descriptive purposesonly and predominantly within the context of a device z-axis andtherefore may be relative to an orientation of a device. Hence, a firstmaterial “over” a second material in the context of a figure providedherein may also be “under” the second material if the device is orientedupside-down relative to the context of the figure provided. In thecontext of materials, one material disposed over or under another may bedirectly in contact or may have one or more intervening materials.Moreover, one material disposed between two materials may be directly incontact with the two layers or may have one or more intervening layers.In contrast, a first material “on” a second material is in directcontact with that second material. Similar distinctions are to be madein the context of component assemblies.

The term “between” may be employed in the context of the z-axis, x-axisor y-axis of a device. A material that is between two other materialsmay be in contact with one or both of those materials, or it may beseparated from both of the other two materials by one or moreintervening materials. A material “between” two other materials maytherefore be in contact with either of the other two materials, or itmay be coupled to the other two materials through an interveningmaterial. A device that is between two other devices may be directlyconnected to one or both of those devices, or it may be separated fromboth of the other two devices by one or more intervening devices.

Here, multiple non-silicon semiconductor material layers may be stackedwithin a single fin structure. The multiple non-silicon semiconductormaterial layers may include one or more “P-type” layers that aresuitable (e.g., offer higher hole mobility than silicon) for P-typetransistors. The multiple non-silicon semiconductor material layers mayfurther include one or more “N-type” layers that are suitable (e.g.,offer higher electron mobility than silicon) for N-type transistors. Themultiple non-silicon semiconductor material layers may further includeone or more intervening layers separating the N-type from the P-typelayers. The intervening layers may be at least partially sacrificial,for example to allow one or more of a gate, source, or drain to wrapcompletely around a channel region of one or more of the N-type andP-type transistors. The multiple non-silicon semiconductor materiallayers may be fabricated, at least in part, with self-aligned techniquessuch that a stacked CMOS device may include both a high-mobility N-typeand P-type transistor with a footprint of a single finFET.

For the purposes of present disclosure, the terms “spin” and “magneticmoment” are used equivalently. More rigorously, the direction of thespin is opposite to that of the magnetic moment, and the charge of theparticle is negative (such as in the case of electron).

It is pointed out that those elements of the figures having the samereference numbers (or names) as the elements of any other figure canoperate or function in any manner similar to that described, but are notlimited to such.

FIG. 1A illustrates a magnetization hysteresis plot 100 for ferromagnet(FM) 101. The plot shows magnetization response to an applied magneticfield for ferromagnet 101. The x-axis of plot 100 is magnetic field ‘H’while the y-axis is magnetization ‘m’. For FM 101, the relationshipbetween ‘H’ and ‘m’ is not linear and results in a hysteresis loop asshown by curves 102 and 103. The maximum and minimum magnetic fieldregions of the hysteresis loop correspond to saturated magnetizationconfigurations 104 and 106, respectively. In saturated magnetizationconfigurations 104 and 106, FM 101 has stable magnetizations. In thezero magnetic field region 105 of the hysteresis loop, FM 101 does nothave a definite value of magnetization, but rather depends on thehistory of applied magnetic fields. For example, the magnetization of FM101 in configuration 105 can be either in the +x direction or the −xdirection for an in-plane FM. As such, changing or switching the stateof FM 101 from one magnetization direction (e.g., configuration 104) toanother magnetization direction (e.g., configuration 106) is timeconsuming resulting in slower nanomagnets response time. It isassociated with the intrinsic energy of switching proportional to thearea in the graph contained between curves 102 and 103.

In some embodiments, FM 101 is formed of CFGG (i.e., Cobalt (Co), Iron(Fe), Germanium (Ge), or Gallium (Ga) or a combination of them). In someembodiments, FM 101 comprises one or more of Co, Fe, Ni alloys andmultilayer hetro-structures, various oxide ferromagnets, garnets, orHeusler alloys. Heusler alloys are ferromagnetic metal alloys based on aHeusler phase. Heusler phases are intermetallic with certain compositionand face-centered cubic crystal structure. The ferromagnetic property ofthe Heusler alloys are a result of a double-exchange mechanism betweenneighboring magnetic ions. In some embodiments, the Heusler alloyincludes one of: Cu₂MnAl, Cu₂MnIn, Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn,Ni₂MnSb, Ni₂MnGa Co₂MnAl, Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn,Pd₂MnSn, Pd₂MnSb, Co₂FeSi, Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, orMnGaRu.

FIG. 1B illustrates magnetization plot 120 for paramagnet 121. Plot 120shows the magnetization response to an applied magnetic field forparamagnet 121. The x-axis of plot 120 is magnetic field ‘H’ while they-axis is magnetization ‘m’. A paramagnet, as opposed to a ferromagnet,exhibits magnetization when a magnetic field is applied to it.Paramagnets generally have magnetic permeability greater or equal to oneand hence are attracted to magnetic fields. Compared to plot 100, themagnetic plot 120 of FIG. 1B does not exhibit hysteresis which allowsfor faster switching speeds and smaller switching energies between thetwo saturated magnetization configurations 124 and 126 of curve 122. Inthe middle region 125, paramagnet 121 does not have any magnetizationbecause there is no applied magnetic field (e.g., H=0). The intrinsicenergy associated with switching is absent in this case.

In some embodiments, paramagnet 121 comprises a material which includesone or more of: Platinum (Pt), Palladium (Pd), Tungsten (W), Cerium(Ce), Aluminum (Al), Lithium (Li), Magnesium (Mg), Sodium (Na), Cr₂O₃(chromium oxide), CoO (cobalt oxide), Dysprosium (Dy), Dy₂O (dysprosiumoxide), Erbium (Er), Er₂O₃ (Erbium oxide), Europium (Eu), Eu₂O₃(Europium oxide), Gadolinium (Gd), Gadolinium oxide (Gd₂O₃), FeO andFe₂O₃ (Iron oxide), Neodymium (Nd), Nd₂O₃ (Neodymium oxide), KO₂(potassium superoxide), praseodymium (Pr), Samarium (Sm), Sm₂O₃(samarium oxide), Terbium (Tb), Tb₂O₃ (Terbium oxide), Thulium (Tm),Tm₂O₃ (Thulium oxide), or V₂O₃ (Vanadium oxide). In some embodiments,paramagnet 121 comprises dopants which include one or more of: Ce, Cr,Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb. In variousembodiments, the magnet can be either a FM or a paramagnet.

FIGS. 2A-B illustrate a three-dimensional (3D) view 200 andcorresponding top view 220, respectively, of device having an in-planemagnetic tunnel junction (MTJ) stack coupled to a spin orbit coupling(SOC) interconnect, where the MTJ stack includes a free magnet layermuch smaller than a length of the SOC interconnect.

Here, the stack of layers having magnetic junction 221 is coupled to anelectrode 222 comprising spin Hall effect (SHE) or SOC material (or spinorbit torque (SOT) material), where the SHE material converts chargecurrent I_(W) (or Write Current) to Spin polarized current Is. Thedevice of FIG. 2A forms a three-terminal memory cell with SHE inducedwrite mechanism and MTJ based read-out. Spin Hall effect is arelativistic spin-orbit coupling phenomenon that can be used toelectrically generate or detect spin currents in non-magnetic systems.

When an in-plane current is applied to heavy-metal/ferromagnet bilayersystems, this in-plane current gives rise to spin accumulation in theferromagnet via sping orbit interactions. The spin accumulation in thefree ferromagnet leads to torques (e.g., SOT) or effective fields actingon the magnetization, thus switching the magnetization of the freeferromagnet. The SOT has two components with differentsymmetries—Slonczewski-like torque and field-like torque. The origin ofthe SOT is generally attributed to the bulk spin Hall effect in theheavy metal. The specific structures of the SOT switching schemedemonstrated here are categorized into two types according to thedirection of the easy axis of the ferromagnet.

FIG. 2A illustrates the easy axis to be in-plane and orthogonal to thecurrent, while FIG. 4A illustrates the easy axis to be perpendicular tothe film plane (or device). The switching dynamics of the two aredifferent.

The device of FIG. 2A comprises magnetic junction 221, SHE Interconnector electrode 222, and non-magnetic metal(s) 223 a/b. In one example, MTJ221 comprises layers 221 a, 221 b, and 221 c. In some embodiments,layers 221 a and 221 c are ferromagnetic layers. In some embodiments,layer 221 b is a metal or a tunneling dielectric.

For example, when the magnetic junction is a spin valve, layer 221 b ismetal or a metal oxide (e.g., a non-magnetic metal such as Al and/or itsoxide) and when the magnetic junction is a tunneling junction, thenlayer 221 b is a dielectric (e.g. MgO, Al₂O₃). One or both ends alongthe horizontal direction of SHE Interconnect 222 is formed ofnon-magnetic metals 223 a/b. Additional layers 221 d, 221 e, 221 f, and221 g can also be stacked on top of layer 221 c. In some embodiments,layer 221 g is a non-magnetic metal electrode.

So as not to obscure the various embodiments, the magnetic junction isdescribed as a magnetic tunneling junction (MTJ). However, theembodiments are also applicable for spin valves. A wide combination ofmaterials can be used for material stacking of magnetic junction 221.For example, the stack of layers 221 a, 221 b, 221 c, 221 d, 221 e, 221f, and 221 g are formed of materials which include: Co_(x)Fe_(y)B_(z),MgO, Co_(x)Fe_(y)B_(z), Ru, Co_(x)Fe_(y)B_(z), IrMn, and Ru,respectively, where ‘x’, ‘y’; and ‘z’ are fractions of elements in thealloys. Other materials may also be used to form MTJ 221. MTJ 221 stackcomprises free magnetic layer 221 a, MgO tunneling oxide 221 b, a fixedmagnetic layer 221 c/d/e which is a combination of CoFe, Ru, and CoFelayers, respectively, referred to as Synthetic Anti-Ferromagnet (SAF),and an Anti-Ferromagnet (AFM) layer 221 f The SAF layer has theproperty, that the magnetizations in the two CoFe layers are opposite,and allows for cancelling the dipole fields around the free magneticlayer such that a stray dipole field will not control the free magneticlayer.

In some embodiments, the free and fixed magnetic layers (221 a and 221c, respectively) are ferromagnets (FMs) that are formed of CFGG (i.e.,Cobalt (Co), Iron (Fe), Germanium (Ge), or Gallium (Ga) or a combinationof them). In some embodiments, FM 221 a/c are formed from Heusleralloys. Heusler alloys are ferromagnetic metal alloys based on a Heuslerphase. Heusler phases are intermetallic with certain composition andface-centered cubic crystal structure. The ferromagnetic property of theHeusler alloys are a result of a double-exchange mechanism betweenneighboring magnetic ions. In some embodiments, the Heusler alloyincludes one of: Cu₂MnAl, Cu₂MnIn, Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn,Ni₂MnSb, Ni₂MnGa Co₂MnAl, Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn,Pd₂MnSn, Pd₂MnSb, Co₂FeSi, Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, orMnGaRu.

The thickness of a ferromagnetic layer (e.g., fixed or free magneticlayer) may determine its equilibrium magnetization direction. Forexample, when the thickness of the ferromagnetic layer 221 a/c is abovea certain threshold (depending on the material of the magnet, e.g.approximately 1.5 nm for CoFe), then the ferromagnetic layer exhibitsmagnetization direction which is in-plane. Likewise, when the thicknessof the ferromagnetic layer 221 a/c is below a certain threshold(depending on the material of the magnet), then the ferromagnetic layer221 a/c exhibits magnetization direction which is perpendicular to theplane of the magnetic layer as illustrated with reference to FIGS. 4A-B.

Other factors may also determine the direction of magnetization. Forexample, factors such as surface anisotropy (depending on the adjacentlayers or a multi-layer composition of the ferromagnetic layer) and/orcrystalline anisotropy (depending on stress and the crystal latticestructure modification such as FCC (face centered cubic lattice), BCC(body centered cubic lattice), or L1₀-type of crystals, where L1₀ is atype of crystal class which exhibits perpendicular magnetizations), canalso determine the direction of magnetization.

Referring back to FIG. 2A, in some embodiments, SHE interconnect 222 (orthe write electrode) includes 3D materials such as one or more ofβ-Tantalum (β-Ta), Ta, β-Tungsten (β-W), W, Pt, Copper (Cu) doped withelements such as Iridium, Bismuth and any of the elements of 3d, 4d, 5dand 4f, 5f periodic groups in the Periodic Table which may exhibit highspin orbit coupling. In some embodiments, SHE Interconnect 222transitions into high conductivity non-magnetic metal(s) 223 a/b toreduce the resistance of SHE Interconnect 222. The non-magnetic metal(s)223 a/b include one or more of: Cu, Co, α-Ta, Al, CuSi, or NiSi.

In FIG. 2A, the switching layer 221 a has its easy axis along the plane(e.g., y plane) direction. For this type, an external field along thez-axis, Hz, is applied to break the symmetry and achieve bipolarswitching. Assuming that the driving force for switching originates fromthe spin Hall effect in interconnect 222, the critical current densityJ, is given by:

$J_{c} = {\frac{2e}{h}\frac{\alpha\; M_{s}t_{F}}{\theta_{SH}^{eff}}\left( {H_{K,{i\; n}}^{eff} + \frac{H_{K,{out}}^{eff}}{2}} \right)}$where α is the Gilbert damping constant, e is the elementary charge, his the Dirac contact, θ_(SH) ^(eff) is the effective spin Hall angle,M_(s) is the saturation magnetization, t_(F) is the thickness of theferromagnet layer 221 a along the z-direction, H_(K,in) ^(eff) isin-plane effective anisotropy field, and H_(K,out) ^(eff) is theout-of-plane effective anisotropy field of the ferromagnet layer 221 a.

In this example, the applied current I_(w) is converted into spincurrent I_(s) by SHE Interconnect 222 (also referred to as the spinorbit coupling interconnect). This spin current switches the directionof magnetization of the free layer and thus changes the resistance ofMTJ 221. However, to read out the state of MTJ 221, a sensing mechanismis needed to sense the resistance change.

The magnetic cell is written by applying a charge current via SHEInterconnect 222. The direction of the magnetic writing in free magnetlayer 221 a is decided by the direction of the applied charge current.Positive currents (e.g., currents flowing in the +y direction) produce aspin injection current with transport direction (along the +z direction)and spins pointing to the +x direction. The injected spin current inturn produces spin torque to align the free magnet 221 a (coupled to SHElayer 222 of SHE material) in the +x direction. Negative currents (e.g.,currents flowing in the −y direction) produce a spin injection currentwith transport direction (along the +z direction) and spins pointing tothe −x direction. The injected spin current in-turn produces spin torqueto align the free magnet 221 a (coupled to the SHE material of layer222) in the −x direction. In some embodiments, in materials with theopposite sign of the SHE/SOC effect, the directions of spin polarizationand thus of the free layer magnetization alignment are reversed comparedto the above. In some embodiments, the magnets 221 a and/or 221 c areparamagnets. In some embodiments, the magnets 221 a and/or 221 c can bea combination of ferromagnets or paramagnets. For example, magnet 221 ais a ferromagnet while magnet 221 c is a paramagnet. In another example,magnet 221 c is a ferromagnet while magnet 221 a is a paramagnet.

FIG. 2C illustrates a cross-section 230 of SOC interconnect 222 withelectrons having their spins polarized in-plane and deflected up anddown resulting from a flow of charge current. In this example, positivecharge current represented by J_(c) produces spin-front (e.g., in the +xdirection) polarized current 301 and spin-back (e.g., in the −xdirection) polarized current 302. The injected spin current {right arrowover (I_(s))} generated by a charge current {right arrow over (I_(c))}in the write electrode 222 is given by:{right arrow over (I _(s))}=P _(SHE)(w,tλ _(sp),θ_(SHE))({right arrowover (I _(c))}×{circumflex over (z)})  (1)where, the vector of spin current {right arrow over (I_(s))}={rightarrow over (I_(↑))}−{right arrow over (I_(↓))} points in the directionof transferred magnetic moment and has the magnitude of the differenceof currents with spin along and opposite to the spin polarizationdirection, {circumflex over (z)} is the unit vector perpendicular to theinterface, P_(SHE) is the spin Hall injection efficiency which is theratio of magnitude of transverse spin current to lateral charge current,w is the width of the magnet, t is the thickness of the SHE Interconnect(or write electrode) 222, λ_(sf) is the spin flip length in SHEInterconnect 222, θ_(SHE) is the spin Hall angle for SHE Interconnect222 to free ferromagnetic layer interface.

The injected spin angular momentum per unit time responsible for thespin torque is given by:{right arrow over (S)}=h{right arrow over (I _(s))}/2e  (2)

The generated spin up and down currents 231/232 are equivalent to thespin polarized current per unit area (e.g., {right arrow over (J_(s))})given by:{right arrow over (J _(s))}=θ_(SHE)({right arrow over (J_(c))}×{circumflex over (z)})  (3)

This spin to charge conversion is based on Tunnel Magneto Resistance(TMR) which is highly limited in the signal strength generated. The TMRbased spin to charge conversion has low efficiency (e.g., less thanone).

FIGS. 3A-B illustrate a 3D view 300 and corresponding top view 320,respectively, of device having an in-plane MTJ stack coupled to SOCinterconnect 222. Compared to the device of FIGS. 2A-B, here, switchinglayer 321 a has easy axis in the film plane (e.g., y plane) andcollinear with the current along the y-axis. The fixed magnet 321 c alsohas magnetization along the y-plane. Material wise, magnets 321 a/c arethe same as magnets 221 a/c, but with different magnetic orientationalong the same plane. In some embodiments, the easy axis is parallel tothe current flowing along the y axis. With the application of anexternal magnetic field, Hz, along the z direction, bipolar switching isachieved.

FIGS. 4A-C illustrate a 3D view 400 and corresponding top view 420,respectively, of device having an out-of-plane MTJ stack coupled to SOCinterconnect 222. Compared to the embodiments of FIGS. 2-3, here freeand fixed magnet layers (or structures) 421 a and 421 c, respectively,have perpendicular magnetic anisotropy (PMA). For example, fixed magnetstructure 421 c has a magnetization pointing along the z-direction andis perpendicular to the x-y plane of the device 400. Likewise, freemagnet structure 421 a has a magnetization pointing along thez-direction and is perpendicular to the x-y plane of the device 400.

In some embodiments, the magnets with PMA comprise a stack of materials,wherein the materials for the stack are selected from a group consistingof: Co and Pt; Co and Pd; Co and Ni; MgO, CoFeB, Ta, CoFeB, and MgO;MgO, CoFeB, W, CoFeB, and MgO; MgO, CoFeB, V, CoFeB, and MgO; MgO,CoFeB, Mo, CoFeB, and MgO; Mn_(x)Ga_(y); materials with L1₀ symmetry;and materials with tetragonal crystal structure. In some embodiments,the magnet with PMA is formed of a single layer of one or morematerials. In some embodiments, the single layer is formed of MnGa.

L1₀ is a crystallographic derivative structure of an FCC (face centeredcubic lattice) structure and has two of the faces occupied by one typeof atom and the corner and the other face occupied with the second typeof atom. When phases with the L1₀ structure are ferromagnetic themagnetization vector usually is along the [0 0 1] axis of the crystal.Examples of materials with L1₀ symmetry include CoPt and FePt. Examplesof materials with tetragonal crystal structure and magnetic moment areHeusler alloys such as CoFeAl, MnGe, MnGeGa, and MnGa.

In some embodiments, the free and fixed magnetic layers (421 a and 421c, respectively) are FMs that are formed of CFGG. In some embodiments,FM 421 a/c are formed from Heusler alloys. Heusler alloys areferromagnetic metal alloys based on a Heusler phase. Heusler phases areintermetallic with certain composition and face-centered cubic crystalstructure. The ferromagnetic property of the Heusler alloys are a resultof a double-exchange mechanism between neighboring magnetic ions. Insome embodiments, the Heusler alloy includes one of: Cu₂MnAl, Cu₂MnIn,Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn, Ni₂MnSb, Ni₂MnGa Co₂MnAl, Co₂MnSi,Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn, Pd₂MnSn, Pd₂MnSb, Co₂FeSi, Co₂FeAl,Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, or MnGaRu.

In some embodiments, the magnets 421 a and/or 421 c can be a combinationof ferromagnets or paramagnets. For example, magnet 421 a is aferromagnet while magnet 421 c is a paramagnet. In another example,magnet 421 c is a ferromagnet while magnet 221 a is a paramagnet. Insome embodiments, magnets 421 a and/or 421 c are paramagnets.

In FIG. 4A, the switching layer 421 a has its easy axis along theout-of-plane (z) direction. For this type, an external field along they-axis, H_(y), is applied to break the symmetry and achieve bipolarswitching. Assuming that the driving force for switching originates fromthe spin Hall effect in interconnect 222, the critical current densityJc is given by:

$J_{c} = {\frac{2e}{h}\frac{M_{s}t_{F}}{\theta_{SH}^{eff}}\left( {\frac{H_{K}^{eff}}{2} - \frac{H_{y}}{\sqrt{2}}} \right)}$

where e is the elementary charge, h is the Dirac contact, θ_(SH) ^(eff)is the effective spin Hall angle, and M_(s), t_(F), and H_(K) ^(eff) arethe saturation magnetization, thickness and effective anisotropy fieldof the ferromagnet layer 421 a, respectively.

In some embodiments, SHE interconnect 222 comprises a spin orbit 2Dmaterial which includes one or more of: graphene, TiS₂, WS₂, MOS₂,TiSe₂, WSe₂, MoSe₂, B₂D₃, Sb₂S₃, Ta₂S, Re₂S₇, LaCPS₂, LaOAsS₂, ScOBiS₂,GaOBiS₂, AlOBiS₂, LaOSbS₂, BiOBiS₂, YOBiS₂, InOBiS₂, LaOBiSe₂, TiOBiS₂,CeOBiS₂, PrOBiS₂, NdOBiS₂, LaOBiS₂, or SrFBiS₂. In some embodiments, theSHE interconnect 222 comprises spin orbit material which includes one ofa 2D material or a 3D material, wherein the 3D material is thinner thanthe 2D material. In some embodiments, the SHE interconnect 222 comprisesa spin orbit material which includes materials that exhibitRashba-Bychkov effect.

In some embodiments, the 2D materials include one or more of: Mo, S, W,Se, Graphene, MoS₂, WSe₂, WS₂, or MoSe₂. In some embodiments, the 2Dmaterials include an absorbent which includes one or more of: Cu, Ag,Pt, Bi, Fr, or H absorbents. In some embodiments, the SOC structurescomprise a spin orbit material which includes materials that exhibitRashba-Bychkov effect. In some embodiments, material which includesmaterials that exhibit Rashba-Bychkov effect comprises materials ROCh₂,where ‘R’ includes one or more of: La, Ce, Pr, Nd, Sr, Sc, Ga, Al, orIn, and where “Ch” is a chalcogenide which includes one or more of: S,Se, or Te.

While the embodiments of FIGS. 2-3 illustrate both magnets havingmagnetizations in the same plane (e.g., either in-plane or perpendicularrelative to the x-y plane of the device), the magnetization direction offixed and free magnets can be in different planes. For example, fixedmagnetic layer 221 c is perpendicular relative to the magnetizationdirection of free magnetic layer 221 a (e.g., magnetization directionsof the free and fixed magnetic layers are not parallel, rather they areorthogonal). In another example, the magnetization direction of freemagnetic layer 221 a is in-plane (e.g., along the x-y plane of thedevice) while the magnetization direction of fixed magnetic layer 221 cis perpendicular to the x-y plane of the device. In another case,magnetization direction of fixed free magnetic layer 221 a is in-plane(e.g., along the x-y plane of the device) while the magnetizationdirection of fixed magnetic layer 221 c is perpendicular to the x-yplane of the device.

The switching dynamics of device 300 of FIG. 3A is similar to those ofdevice 400 of FIG. 4A, where the magnetization polarity changes as soonas the torque is exerted. This is in contrast to the dynamics device 200of FIG. 2A, where many precessions take place before the polaritychanges. As such, devices 300/400 allow a shorter switching time thanthe switching time of device 200, in accordance with some embodiments.

FIGS. 5A-C illustrate a mechanism for switching an MTJ memory device(e.g., device 400) formed on spin orbit torque electrode 222.

FIG. 5A illustrates an MTJ memory device (e.g., device 400) where MTJ421 is disposed on a spin orbit torque electrode 222, and where amagnetization 554 of the free magnet 421 a (also referred to as storagelayer 421 a) is in the same direction as a magnetization 556 of thefixed magnet 421 c. In some embodiments, the direction of magnetization554 of the storage layer 421 a and the direction of magnetization 556 ofthe fixed magnet 421 c are both in the negative z-direction asillustrated in FIG. 5A. When the magnetization 554 of the storage layer421 a is in the same direction as a magnetization 556 of the fixedmagnet 421 c, MTJ memory device 400 is in a low resistance state.Conversely, when the magnetization 554 of the storage layer 421 a is inthe opposite direction as a magnetization 556 of the fixed magnet 421 c,MTJ memory device 400 is in a high resistance state.

FIG. 5B illustrates a SOT memory device (e.g., device 400) switched to ahigh resistance state. In an embodiment, a reversal in the direction ofmagnetization 554 of the storage layer 421 a in FIG. 5B compared to thedirection of magnetization 554 of the storage layer 421 a is broughtabout by (a) inducing a spin hall current 568 in the spin orbit torqueelectrode 222 in the y-direction and (b) by applying a spin torquetransfer current 570, i_(sTTM), (by applying a positive voltage atterminal B with respect to ground C), and/or (c) by applying an externalmagnetic field, H_(y), in the y-direction.

In an embodiment, a charge current 560 is passed through the spin orbittorque electrode 222 in the negative y-direction (by applying a positivevoltage at terminal A with respect to ground C). In response to thecharge current 560, an electron current 562 flows in the positivey-direction. The electron current 562 includes electrons with twoopposite spin orientations and experience a spin dependent scatteringphenomenon in the spin orbit torque electrode 222.

The electron current 562 includes electrons with two opposing spinorientations, a type I electron 566, having a spin oriented in thenegative x-direction and a type II electron 564 having a spin orientedin the positive x-direction. In some embodiments, electrons constitutingthe electron current 562 experience a spin dependent scatteringphenomenon in the spin orbit torque electrode 222. The spin dependentscattering phenomenon is brought about by a spin-orbit interactionbetween the nucleus of the atoms in the spin orbit torque electrode 222and the electrons in the electron current 562. The spin dependentscattering phenomenon causes type I electrons 566, whose spins areoriented in the negative x-direction, to be deflected upwards towards anuppermost portion of the spin orbit torque electrode 222 and type IIelectrons 564 whose spins are oriented in the positive x-direction to bedeflected downwards towards a lowermost portion of the spin orbit torqueelectrode 222.

The separation between the type I electron spin angular moment 566 andthe type II electron spin angular moment 564 induces a polarized spindiffusion current 568 in the spin orbit torque electrode 222. In someembodiments, the polarized spin diffusion current 568 is directedupwards toward the free magnet 421 a of the MTJ memory device 400 asdepicted in FIG. 5B. The polarized spin diffusion current 568 induces aspin hall torque on the magnetization 554 of the free magnet 421 a. Thespin hall torque rotates the magnetization 554 to a temporary statepointing in the negative x-direction. In some embodiments, to completethe magnetization reversal process an additional torque is applied. Thei_(STTM) current 570 flowing through the MTJ memory device 400 exerts anadditional torque on the magnetization 554 of the storage layer 421 a.The combination of spin hall torque and spin transfer torque causesflipping of magnetization 554 in the storage layer 421 a from theintermediate magnetization state (negative x-direction) to a positivez-direction illustrated in FIG. 5B. In some embodiments, an additionaltorque can be exerted on the storage layer 421 a by applying an externalmagnetic field, H_(y), in the y-direction, as illustrated in FIG. 5B,instead of applying an i_(STTM) current 570.

FIG. 5C illustrates an SOT memory device switched to a low resistancestate. In an embodiment, a reversal in the direction of magnetization554 of the storage layer 421 a in FIG. 5C compared to the direction ofmagnetization 554 of the storage layer 421 a in FIG. 5B is brought aboutby (a) reversing the direction of the spin hall current 568 in the spinorbit torque electrode 222 and (b) by reversing the direction of thei_(STTM) current 570, and/or (c) by reversing the direction of theexternal magnetic field, H_(y).

FIG. 5D illustrates a cross-section of out-of-plane MTJ memory device580 (e.g. device of FIG. 4A) with spin directions in an SOT/AFMinterconnect 222 of the device when temperature (T) is below a blockingtemperature (T_(blocking)) of the AFM of the interconnect 222. Onechallenge in using the AFM materials for the SOC electrode (orinterconnect) 222 is that the AFM materials typically have low blockingtemperature. If the AFM is deposited along one orientation (e.g.,y-direction) by annealing and field cooling, then due to passing ofelectric current 560 through the SOT/AFM electrode 222, the AFM of theelectrode 222 can be heated above its blocking temperature T_(blocking)and will get re-magnetized depending upon the direction of the magneticfield it senses. This will affect the reliability of the SOT MRAMoperation. In this example, the operating temperature is below theblocking temperature, and so the directions of spins 591 in electrode222 show zero net magnetization because spins in alternating layers arein opposite direction as shown by spins 581.

FIG. 5E illustrates a cross-section of out-of-plane MTJ memory device590 (e.g. device of FIG. 4A) with spin directions in the SOT/AFMinterconnect 222 of the device when temperature (T) is above theblocking temperature (T_(blocking)) of the AFM in interconnect 222.Compared to FIG. 5E, here when temperature is above the blockingtemperature, the spins in the SOT/AFM electrode 222 become random asshown by spins 591. These random spin directions negatively affect thereliability of the PSOT magnetic memory operation.

One way to solve the problem of random spins is to adjust the thicknessof the AFM material of SOT/AFM electrode 222. For example, by increasingthe thickness of the AFM material in z-direction. Blocking temperatureis dependent on the thickness and the grain size of AFM materials. Byincreasing the thickness, the blocking temperature is increased. Variousembodiments here change the material composition of the SOT/AFMelectrode 222 to increase the blocking temperature of the AFM materialof the SOT/AFM. For example, the blocking temperature of the AFMmaterial is increased to 120 degrees or more while continuing to providehigh spin orbit torque to the fee magnet 421 a.

FIG. 6A illustrates plot 620 showing write energy-delay conditions forone transistor and one MTJ with SHE material (e.g., one of device 200 or300) compared to traditional MTJs. FIG. 6B illustrates plot 630 showingwrite energy-delay conditions for one transistor and one MTJ with SHEmaterial (e.g., one of device 200 or 300) compared to traditional MTJs.Here, the x-axis is energy per write operation in femto-Joules (0) whilethe y-axis is delay in nano-seconds (ns).

Here, the energy-delay trajectory of SHE and MTJ devices (e.g., one ofdevice 200 or 300) are compared for in-plane magnet switching as theapplied write voltage is varied. The energy-delay relationship (forin-plane switching) can be written as:

${E(\tau)} = {{R_{write}I_{co}^{2}\;\frac{\left( {\tau + {\tau_{0}{\ln\left( \frac{\pi}{2\theta_{0}} \right)}}} \right)^{2}}{\tau}} = {\frac{4}{h^{2}}\frac{R_{write}}{P^{2}}\frac{1}{\tau}\left( {\mu_{0}e\;\alpha\;\frac{M_{s}}{2}\left( {\tau + {\tau_{0}{\ln\left( \frac{\pi}{2\theta_{0}} \right)}}} \right)^{2}} \right)W}}$where R_(write) is the write resistance of the device (resistance of SHEelectrode or resistance of MTJ-P or MTJ-AP, where MTJ-P is a MTJ withparallel magnetizations while MTJ-AP is an MTJ with anti-parallelmagnetizations, μ₀ is vacuum permeability, e is the electron charge. Theequation shows that the energy at a given delay is directly proportionalto the square of the Gilbert damping α. Here the characteristic time,τ₀=^(M) ^(s) ^(Ve)/_(I) _(c) _(Pμ) _(B) varies as the spin polarizationvaries for various SHE metal electrodes (e.g., 623, 624, 625). Plot 620shows five curves 621, 622, 623, 624, and 625. Curves 621 and 622 showwrite energy-delay conditions using traditional MTJ devices without SHEmaterial.

For example, curve 621 shows the write energy-delay condition caused byswitching a magnet from anti-parallel (AP) to parallel (P) state, whilecurve 622 shows the write energy-delay condition caused by switching amagnet from P to AP state. Curves 622, 623, and 624 show writeenergy-delay conditions of an MTJ with SHE material. Clearly, writeenergy-delay conditions of an MTJ with SHE material (e.g., one of device200 or 300) is much lower than the write energy-delay conditions of anMTJ without SHE material (device not shown). While the writeenergy-delay of an MTJ with SHE material (e.g., one of device 200 or300) improves over a traditional MTJ without SHE material, furtherimprovement in write energy-delay is desired.

FIG. 6B illustrates plot 630 comparing reliable write times for spinHall MRAM and spin torque MRAM. There are three cases considered in plot630. Waveform 631 is the write time for in-plane MTJ, waveform 632 isthe write time for PMA MTJ, and waveform 633 is the write time for spinHall MTJ. The cases considered here assume a 30×60 nm magnet with 40 kTenergy barrier and 3.5 nm SHE electrode thicknesses. The energy-delaytrajectories of the devices are obtained assuming a voltage sweep from 0V to 0.7 V in accordance to voltage restrictions of scaled CMOS. Theenergy-delay trajectory of the SHE-MTJ devices exhibits broadly twooperating regions A) Region 1 where the energy-delay product isapproximately constant (τ_(d)<^(M) ^(s) ^(Ve)/_(I) _(c) _(Pμ) _(B) ),and Region 2 where the energy is proportional to the delay τ_(d)>^(M)^(s) ^(Ve)/_(I) _(c) _(Pμ) _(B) . The two regions are separated byenergy minima at τ_(opt)=^(M) ^(s) ^(Ve)/_(I) _(c) _(Pμ) _(B) whereminimum switching energy is obtained for the spin torque devices.

The energy-delay trajectory of the STT-MTJ (spin transfer torque MTJ)devices is limited with a minimum delay of 1 ns for in-plane devices at0.7 V maximum applied voltage, the switching energy for P-AP and AP-Pare in the range of 1 pJ/write. In contrast, the energy-delay trajectoryof SHE-MTJ (in-plane anisotropy) devices can enable switching times aslow as 20 ps (β-W with 0.7 V, 20 fJ/bit) or switching energy as small as2 fJ (β-W with 0.1 V, 1.5 ns switching time).

FIG. 6C illustrates plot 630 showing remnant pinning field curve for atop spin valve pinned by 200 A of PtMn. PtMn, like IrMn, is an AFMmaterial. Here, the x-axis is temperature in Celsius (C), and the y-axisis magnetic field in Oersted (Oe) at the interface of SOT/AFMinterconnect 222 and the magnetic junction. The plot shows that around350° C., the magnetic field at the interface suddenly falls from 1280 Oeto below zero. This sudden change in the magnetic field at the interfacecauses operational reliability issues for the magnetic device using PtMnas AFM.

FIG. 6D illustrates plot 640 showing unblocked ratio in spin-valvestructures with the different antiferromagnetic biasing layers. Thebiasing layers are antiferromagnetic layers applying magnetic fieldbias. Here, the lines in the plot are hyperbolic tangent fits. FIG. 6Eillustrates plot 650 showing blocking temperature distribution in thecorresponding structures. The dashed lines correspond to the regionwhere no experimental data points were taken. Plot 650 shows theblocking temperatures for different AFM materials—FeMn, CrPdMn, IrMn,PtMn, and NiMn.

FIGS. 7A-B illustrate a 3D view 700 and corresponding cross-section view720, respectively, of a device having a magnetic junction with magnetshaving perpendicular magnetizations, and a doped SOT/AFM interconnectresulting in higher blocking temperature, according to some embodimentsof the disclosure.

The device of FIG. 7A is similar to the device of FIG. 4A. Here, thefree magnet 421 a of FIG. 4A is replaced with a structure comprising astack of layers or films. The magnetic junction is illustrated byreference sign 721 where the layers under layer 221 b (e.g., dielectricor metal/metal-oxide) together form the free magnet structure comprisingthe free magnet of the junction.

In some embodiments, the structure replacing free magnet 421 a comprisesat least two free magnets 721 aa and 721 ac with a coupling layer 721 abbetween them, where one of the free magnet couples to (or is adjacentto) an insert layer 721. In some embodiments, the insert layer 721couples to (or is adjacent to) the SOC electrode 222.

In some embodiments, SOC/AFM interconnect 222 of FIG. 4A comprises dopedAFM and is labeled as SOC/AFM interconnect 722. In some embodiments, theAFM of SOT interconnect 722 is doped by one of: oxygen, nitrogen orheavy metal with large spin flip length and small thermal mobility suchas Ta, Pt, W, Mo, Co, Ni and others. In some embodiments, the AFM ofinterconnect 722 applies SOT and in-plane exchange bias to the freelayer 721 aa/421 a. In some embodiments, the thickness tsoc ofinterconnect 722 is in the range of 0.5 nm to 20 nanometers.

In some embodiments, the AFM of interconnect 722 is doped with one of:Co, Fe, Ni, MnGa, MnGeGa, or Bct-Ru. In some embodiments, the dopingmaterial can be: IrMn, PtMn, NiMn or other triangular, Kagomi, chiral orhexagonal antiferromagnetic material and in their single crystal form ortheir amorphous alloys in various compositions. In some embodiments, thedoping can be done by co-sputtering and/or reactive ion sputtering incase of oxygen or nitrogen. In some embodiments, the oxygen and/orfluorine doping can be done by plasma treatments.

One advantage of doping or co-sputtering the low temperaturehigh-efficiency SOT/AFM material of electrode 722 with heavy metals,oxygen, nitrogen, or other AFM with high blocking temperature is that itwill allow for higher current and higher temperature operation withoutthe loss of AFM nature. Doping or co-sputtering with heavier metals willincrease the blocking temperature of the AFM in electrode 722.Typically, heavy metals are less responsive to diffusion. In someembodiments, doping the SOT/AFM electrode 722 with nitrogen and oxygenhas the potential to increase not just the blocking temperature, but thespin orbit torque generated by the AFM layer as well. This makes thePSOT based MRAM more reliable.

In some embodiments, the other free magnet 721 ac of the free magnetstructure couples to or is adjacent to a dielectric (e.g., when themagnetic junction is an MTJ) or a metal or its oxide (e.g., when themagnetic junction is a spin valve). In some embodiments, the free magnetstructure comprises a first free magnet 721 aa having perpendicularmagnetization that can point substantially along the +z-axis or −z-axisaccording to an external field (e.g., spin torque, spin coupling,electric field); a coupling layer 721 ab; and a second free magnet 721ac having perpendicular magnetization that can point substantially alongthe +z-axis or −z-axis. In various embodiments, the second free magnet721 ac is adjacent to layer 221 b (e.g., dielectric ormetal/metal-oxide).

In some embodiments, the coupling layer 721 ab includes one or more of:Ru, Os, Hs, Fe, or other transition metals from the platinum group ofthe periodic table. In some embodiments, magnets 721 aa, 721 ac, and 724comprise CFGG. In some embodiments, magnets 721 aa, 721 ac, and 724 areformed from Heusler alloys. In some embodiments, the Heusler alloyincludes one or more of Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn,Ni, Pd, Ru, or V. In some embodiments, the Heusler alloy includes oneof: Cu₂MnAl, Cu₂MnIn, Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn, Ni₂MnSb,Ni₂MnGa Co₂MnAl, Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn, Pd₂MnSn,Pd₂MnSb, Co₂FeSi, Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, or MnGaRu.

In some embodiments, magnets 721 aa and 721 ac with PMA comprises astack of materials, wherein the materials for the stack are selectedfrom a group comprising: Co and Pt; Co and Pd; Co and Ni; MgO, CoFeB,Ta, CoFeB, and MgO; MgO, CoFeB, W, CoFeB, and MgO; MgO, CoFeB, V, CoFeB,and MgO; MgO, CoFeB, Mo, CoFeB, and MgO; Mn_(x)Ga_(y); Materials withL1₀ symmetry; or materials with tetragonal crystal structure. In someembodiments, the magnet with PMA is formed of a single layer of one ormore materials. In some embodiments, the single layer comprises Mn andGa (e.g., MnGa).

FIGS. 7C-D illustrate a 3D view 730 and corresponding cross-section view740, respectively, of a device having a magnetic junction with magnetshaving perpendicular magnetizations, and a composite interconnect havingAFM material resulting in higher blocking temperature, according to someembodiments of the disclosure.

The device of FIGS. 7C-D is similar to device of FIGS. 7A-B but for thecomposition of interconnect 722. Here, interconnect 722 is replaced witha composite interconnect 733, in accordance with some embodiments. Insome embodiments, the thickness of to is 0.1 nm to 20 nm. In someembodiments, composite interconnect 733 comprises two or more layers of733 a and 733 b. In some embodiments, the two or more layers of 733 aand 733 b includes AFM material. In various embodiments, layer 733 a,which is directly in contact with insert layer 721, comprises an AFMmaterial that has the highest spin orbit torque compared to other non733 a layers. In some embodiments, the AFM material of interconnect 733applies interfacial in-plane exchange bias to free layer 721 aa. In someembodiments, AFM material includes one of: Ir, Pt, Mn, Pd, or Fe. Insome embodiments, the AFM material is a quasi-two-dimensional triangularAFM including Ni_((1-x))M_(x)Ga₂S₄, where ‘M’ includes one of: Mn, Fe,Co or Zn. In some embodiments, the thickness of to and tb are in therange of 0.1 nm to 8 nm.

In some embodiments, AFM layers 733 a/b are doped by one of: oxygen,nitrogen or heavy metal with large spin flip length and small thermalmobility such as Ta, Pt, W, Mo, Co, Ni and others. In some embodiments,AFM layers 733 a/b are doped with one of: Co, Fe, Ni, MnGa, MnGeGa, orBct-Ru. In some embodiments, doping the layers of SOT/AFM electrode 733with nitrogen and oxygen has the potential to increase not just theblocking temperature, but the spin orbit torque generated by the AFMlayer 733 a coupled to fee layer 721 aa. This makes the PSOT based MRAMof FIGS. 7C-D more reliable.

FIGS. 7E-F illustrate a 3D view 750 and corresponding cross-section view760, respectively, of a device having a magnetic junction with magnetshaving perpendicular magnetizations, and doped SOT/AFM interconnectresulting in higher blocking temperature, and a via comprising anin-plane magnet adjacent to the SOT/AFM interconnect, according to someembodiments of the disclosure.

In some embodiments, the device of FIGS. 7E-F includes an in-plane fixedmagnet 726 adjacent to one of the surfaces of the interconnect 722/733,such free magnet 721 aa is adjacent to the other surface opposite to thesurface of interconnect 722/733. In some embodiments, the in-plane fixedmagnet 726 is thick or long enough in dimensions that results in astable in-plane magnet that applies an effective in-plane field on theperpendicular free magnets 721 aa and/or 721 ac for faster switching offree magnets 721 aa and/or 721 ac. In some embodiments, the in-planefixed magnet thickness tm is in the range of 1 nm to 20 nm. Theeffective in-plane field can be applied via exchange bias interaction ordipole coupling from the in-plane fixed magnet 726. For example,in-plane magnet 726 has a magnetization pointing along the x-directionor y-direction and is parallel to the x-y plane of the device 750. Here,the switching speed of the free magnets in the structure is improved forthe same power consumption over the switching speed of the free magnet421 a of FIG. 4A, at the same time the blocking temperature is increasedby interconnect 722/733.

FIGS. 7G-H illustrate a 3D view 750 and corresponding cross-section view760, respectively, of a device having a magnetic junction with magnetshaving perpendicular magnetizations, and the SOT/AFM interconnectresulting in higher blocking temperature, and a via comprising anin-plane magnet and an AFM one of which is adjacent to the SOT/AFMinterconnect, according to some embodiments of the disclosure.

The device of FIG. 7G is similar to the device of FIG. 7E, but foraddition of AFM 727 in the magnetic via. In some embodiments, thein-plane fixed magnet 726 of the magnetic via is coupled to or isadjacent to an in-plane AFM or synthetic AFM (SAF) 727 also formed inthe magnetic via. The order of the AFM 727 and in-plane fixed magnet 726can be switched. For example, in some embodiments, AFM 727 is adjacentto interconnect 222/722 while the in-plane fixed magnet 726 is below AFM727 and not in direct contact with interconnect 722/733.

In some embodiments, AFM or SAF 727 comprises a material which includesone of: Ir, Pt, Mn, Pd, or Fe. In some embodiments, AFM or SAF 727 is aquasi-two-dimensional triangular AFM including Ni_((1-x))M_(x)Ga₂S₄,where ‘M’ includes one of: Mn, Fe, Co or Zn. In some embodiments, AFM orSAF 727 comprises a pair of fixed magnets 727 a and 727 c with in-planemagnetizations, and a coupling layer 727 b between the fixed magnets 727a and 727 c. In some embodiments, the materials for the fixed magnets727 a/c can be according to any of the materials for magnets discussedherein. In various embodiments, fixed magnets 727 a/c are in-planemagnets. In some embodiments, the material for coupling layer 727 b canbe the same material (or selected from the same group of materials) asthat of coupling layer 721 ab. Technical effect wise, the device of FIG.7G performs similarly to the device of FIG. 7A, and improves switchingspeed of free magnets 721 aa and 721 ac relative to switching speed offree magnet 221 a, and also results in higher blocking temperature.

FIGS. 7I-J illustrate a 3D view 770 and corresponding cross-section view780, respectively, of a device having a magnetic junction with magnetshaving perpendicular magnetizations, where an AFM is embedded in thedoped SOT/AFM interconnect, and a via comprising an in-plane magnetwhich is adjacent to the AFM, according to some embodiments of thedisclosure.

The device of FIG. 7I is similar to the device of FIG. 7G except thatthe AFM 727 is also incorporated outside the magnetic via as AFM 728adjacent to SOC/AFM interconnect 722. In some embodiments, AFM 728 canbehave as an etch stop layer when fabricating SOC/AFM interconnect 722.As such, one or more additional processes for forming an etch stop layeris/are removed. In various embodiments, AFM 728 assists with keeping themagnetization of magnet 726 stable with in-plane magnetization. In someembodiments, AFM 728 also comprises a pair of fixed magnets (not shown)with in-plane magnetizations, and a coupling layer between the fixedmagnets like AFM 727. Technical effect wise, the device of FIG. 7Iperforms similarly to the devices of FIG. 7G, and improves switchingspeed of free magnets 721 aa and 721 ac relative to the switching speedof free magnet 221 a by SHE electrode 222 alone, and also increases theblocking temperature.

In some embodiments, layer 728 comprises an oxide AFM such as BFO whichis adjacent to SOT/AFM electrode 733 or SOT/AFM electrode 222 (withoutthe doping for increasing blocking temperature). In some embodiments,magnetic via is not part of device 770. In other embodiments, magneticvia comprising AFM 727 and/or in-plane magnet 726 is adjacent to theoxide AFM layer 728. In some embodiments, oxide AFM of layer 728increases the blocking temperature of the un-doped SOT/AFM electrode222.

FIG. 8A illustrates a cross-section of a device 800 having a magneticjunction with magnets having perpendicular magnetizations as indicatedby signs 801, 802, and 803, where a free magnet structure of themagnetic junction comprises a stack of magnets with perpendicularmagnetizations, and a via comprising an in-plane magnet and/or an AFM,one of which is adjacent to the SOT/AFM interconnect with higherblocking temperature, according to some embodiments of the disclosure.

The magnetic junction here is illustrated by reference sign 821 wherethe layers under layer 221 b (e.g., dielectric or metal/metal-oxide)together form the structure comprising the free magnet of the junction.The device of FIG. 8A is similar to the device of FIG. 7A except thatthe free magnets 721 aa and 721 ae are replaced with composite magnetshaving multiple layers.

In some embodiments, the composite stack of multi-layer free magnet 821aa includes ‘n’ layers of first material and second material. Forexample, the composite stack comprises layers 821 aa _(1-n) and 821 ab_(1-n) stacked in an alternating manner, where ‘n’ has a range of 1 to1₀. In some embodiments, the first material includes one of: Co, Ni, Fe,or an Heusler alloy. In some embodiments, the second material includesone of: Pt, Pd, Ir, Ru, or Ni. In some embodiments, the Heusler alloyincludes one or more of Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn,Ni, Pd, Ru, or V. In some embodiments, the Heusler alloy includes oneof: Cu₂MnAl, Cu₂MnIn, Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn, Ni₂MnSb,Ni₂MnGa Co₂MnAl, Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn, Pd₂MnSn,Pd₂MnSb, Co₂FeSi, Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, or MnGaRu. Insome embodiments, the first material has a thickness t1 in a range of0.6 nm to 2 nm. In some embodiments, the second material has a thicknesst2 in a range of 0.1 nm to 3 nm. While the embodiments here show firstmaterial being at the bottom followed by the second material, the ordercan be reversed without changing the technical effect. In variousembodiments, free magnet structure 821 aa is coupled to interconnect722/733, which increases the blocking temperature.

In some embodiments, composite stack of multi-layer free magnet 821 bbincludes ‘n’ layers of first material and second material. For example,the composite stack comprises layers 821 aa _(1-n) and 821 ab _(1-n)stacked in an alternating manner, where ‘n’ has a range of 1 to 1₀. Insome embodiments, the first material includes one of: Co, Ni, Fe, or aHeusler alloy. In some embodiments, the second material includes one of:Pt, Pd, Ir, Ru, or Ni. In some embodiments, the Heusler alloy includesone or more of Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd,Ru, or V. In some embodiments, the Heusler alloy includes one of:Cu₂MnAl, Cu₂MnIn, Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn, Ni₂MnSb, Ni₂MnGaCo₂MnAl, Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn, Pd₂MnSn, Pd₂MnSb,Co₂FeSi, Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, or MnGaRu. In someembodiments, the first material has a thickness t1 in a range of 0.6 nmto 2 nm. In some embodiments, the second material has a thickness t2 ina range of 0.1 nm to 3 nm. While the embodiments here show firstmaterial being at the bottom followed by the second material, the ordercan be reversed without changing the technical effect.

The embodiments of FIGS. 7A-J can be mixed in any order. For example,the in-plane magnet 726 can be replaced with an AFM magnet, free magnetstructure with free magnets and coupling layer can be replaced with asingle magnet with free magnetization, etc. In some embodiments, themagnets (free and/or fixed) can also be paramagnets.

FIG. 8B illustrates a cross-section of a device 850 having a magneticjunction with magnets having perpendicular magnetizations, where a freemagnet structure and a fixed magnet structure of the magnetic junctioncomprises a stack of magnets with perpendicular magnetizations, and avia comprising an in-plane magnet and/or an AFM, one of which isadjacent to the SOT/AFM interconnect 722/733 with higher blockingtemperature, according to some embodiments of the disclosure.

Here, fixed magnet 221 c of FIG. 8A is replaced with a composite stack.As such, the magnetic junction is labeled as 831. In some embodiments,composite stack of multi-layer fixed magnet 821 cc includes ‘n’ layersof first material and second material. For example, the composite stackcomprises layers 821 aa _(1-n) and 821 ab _(1-n) stacked in analternating manner, where ‘n’ has a range of 1 to 10. In someembodiments, the first material includes one of: Co, Ni, Fe, or Heusleralloy. In some embodiments, the second material includes one of: Pt, Pd,Ir, Ru, or Ni. In some embodiments, the Heusler alloy includes one ormore of Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, orV. In some embodiments, the Heusler alloy includes one of: Cu₂MnAl,Cu₂MnIn, Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn, Ni₂MnSb, Ni₂MnGa Co₂MnAl,Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn, Pd₂MnSn, Pd₂MnSb, Co₂FeSi,Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, or MnGaRu. In some embodiments,the first material has a thickness t3 in a range of 0.6 nm to 2 nm. Insome embodiments, the second material has a thickness t4 in a range of0.1 nm to 3 nm. While the embodiments here show the first material beingat the bottom followed by the second material, the order can be reversedwithout changing the technical effect.

FIG. 8C illustrates a cross-section of a device 850 having a magneticjunction with magnets having perpendicular magnetizations, where a fixedmagnet structure and one of the free magnets of a free magnet structureof the magnetic junction comprises a stack of magnets with perpendicularmagnetizations, and a via comprising an in-plane magnet and/or an AFM,one of which is adjacent to the SOT/AFM interconnect 722/733 with higherblocking temperature, according to some embodiments of the disclosure.Here, free magnet 821 bb of FIG. 8C is replaced with a non-compositefree magnet 721 ac. As such, the magnetic junction is labeled as 851.

FIG. 8D illustrates a cross-section of a device 860 having a magneticjunction with magnets having perpendicular magnetizations, where a fixedmagnet structure of the magnetic junction comprises a stack of magnetswith perpendicular magnetizations, and a via comprising an in-planemagnet and/or an AFM, one of which is adjacent to the SOT/AFMinterconnect 722/733 with higher blocking temperature, according to someembodiments of the disclosure. Here, free magnet 821 aa of FIG. 8D isreplaced with a non-composite free magnet 721 aa. As such, the magneticjunction is labeled as 861.

FIG. 8E illustrates a cross-section of a device 870 having a magneticjunction with magnets having perpendicular magnetizations, where a fixedmagnet structure and one of the free magnets of a free magnet structureof the magnetic junction comprises a stack of magnets with perpendicularmagnetizations, and a via comprising an in-plane magnet and/or an AFM,one of which is adjacent to the SOT/AFM interconnect 722/733 with higherblocking temperature, according to some embodiments of the disclosure.Here, free magnet 821 aa of FIG. 8B is replaced with a non-compositefree magnet 721 aa.

FIG. 8F illustrates a cross-section of a device 880 having a magneticjunction with magnets having perpendicular magnetizations, where a freemagnet structure and a fixed magnet structure of the magnetic junctioncomprises a stack of magnets with perpendicular magnetizations, and avia comprising an in-plane magnet which is adjacent to an AFM embeddedin the SOT/AFM interconnect, according to some embodiments of thedisclosure. Compared to FIG. 8F here, the AFM 727 is removed from themagnetic via and integrated in the SOC interconnect 222 as layer 728. Insome embodiments, layer 728 is an AFM oxide layer which increases theblocking temperature of the interconnect, which now includes SOT/AFM 222and layer 728. In some embodiments, the interconnect or electrodecomprises SOC 222 and layer 728 (e.g., BFO).

FIG. 9A illustrates plot 900 showing spin polarization capturingswitching of a free magnet structure which is exchanged coupled orbiased by a magnetic via under an SOT/AFM interconnect 722/733 withhigher blocking temperature, and an insert layer between the magneticjunction and the interconnect, according to some embodiments of thedisclosure. FIG. 9B illustrates a magnetization plot 920 associated withFIG. 9A, according to some embodiments of the disclosure.

Plot 900 shows switching of the spin orbit torque device with PMA. Here,waveforms 901, 902, and 903 represent the magnetization projections onthe x, y, and z axes, respectively. The magnet starts withz-magnetization of −1. Positive spin orbit torque (SOT) is applied from5 ns (nanoseconds) to 50 ns. It leads to switching the z-magnetizationto 1. Then, a negative spin orbit torque is applied between 120 ns and160 ns. It leads to switching the z-magnetization to 1. This illustrateschange of magnetization in response to write charge current of certainpolarity.

FIG. 9C illustrates a plot 930 showing spin polarization capturingswitching of the free magnet structure which is exchanged coupled orbiased by a magnetic via under the SOT/AFM interconnect 722/733 withhigher blocking temperature, and an insert layer between the magneticjunction and the interconnect, according to some embodiments of thedisclosure. FIG. 9D illustrates a magnetization plot 940 associated withFIG. 9C, according to some embodiments of the disclosure.

Here, waveforms 931, 932, and 933 represent the magnetizationprojections on x, y, and z axes, respectively. The difference from thecase of FIG. 9C is that negative spin orbit torque (SOT) is applied from5 ns to 50 ns. As a result, the z-magnetization remains close to −1.This illustrates the persistence of magnetization in response to writecharge current of opposite polarity.

FIG. 10A-C illustrate cross-sectional views 1000, 1020, and 1030,respectively, of a SOT memory device 1000, 1020, and 1030, respectively,(e.g., any one of devices of FIGS. 7-8) coupled to a transistor and abit line, according to some embodiments.

In an embodiment, the transistor is an n-type transistor MN that has asource region 1002, a drain region 1004 and a gate 1006. The transistorMN further includes a gate contact 1014 disposed above and electricallycoupled to the gate 1006, a source contact 1016 disposed above andelectrically coupled to the source region 1002, and a drain contact 718disposed above and electrically coupled to the drain region 1004. Insome embodiments, an SOT memory device such as an SOT memory device ofFIGS. 7-8 is disposed above the transistor. While the embodiments areillustrated with an n-type transistor MN, the transistor can be replacedwith a p-type transistor.

In some embodiments, the SOT memory device includes a spin orbit torqueelectrode, such as spin orbit torque electrode 722/733 (or electrodecomprising 222/728, where layer 728 is an AFM oxide, or electrodecomprising 722 or 733 with layer 728), a magnetic tunnel junction memorydevice such as MTJ 721/821/831/841/851/861/871 is disposed on the spinorbit torque electrode 722/733, and a conductive interconnect structuresuch as conductive interconnect structure 708 (e.g., structure 708 a/b)disposed on and coupled to the MTJ. In some embodiments, the spin orbittorque electrode 722/733 (or electrode comprising 222/728, where layer728 is an AFM oxide, or electrode comprising 722 or 733 with layer 728)is disposed on the drain contact 718 of the transistor 700.

In some embodiments, the MTJ memory device (e.g., which includes MTJ721/821/831/841/851/861/871) includes individual functional layers thatare described in association with FIGS. 2-8. In some embodiments, thespin orbit torque electrode 722/733 (or electrode comprising 222/728,where layer 728 is an AFM oxide, or electrode comprising 722 or 733 withlayer 728) has a length, L_(SOT) that is less than a distance ofseparation, L_(DS) between the drain contact 1018 and the source contact1016. In some embodiments, a portion of the spin orbit torque electrode722/733 (or electrode comprising 222/728, where layer 728 is an AFMoxide, or electrode comprising 722 or 733 with layer 728) extends abovethe gate electrode 1012 and the gate contact 1014. In some embodiments,a portion of the spin orbit torque electrode 722/733 (or electrodecomprising 222/728, where layer 728 is an AFM oxide, or electrodecomprising 722 or 733 with layer 728) extends over the gate electrode1012. In some embodiments, the spin orbit torque electrode 722/733 (orelectrode comprising 222/728, where layer 728 is an AFM oxide, orelectrode comprising 722 or 733 with layer 728) is in a first y-z planeas illustrated in FIG. 7A.

In some embodiments, the gate contact 1014 is directly below the spinorbit torque electrode 722/733 (or electrode comprising 222/728, wherelayer 728 is an AFM oxide, or electrode comprising 722 or 733 with layer728). In some embodiments, a word-line (WL) contact 1070 is disposedonto the gate contact 1014 on a second y-z plane behind (into the page)the first y-z plane of the spin orbit torque electrode 222. In someembodiments, the spin orbit torque electrode 722/733 (or electrodecomprising 222/728, where layer 728 is an AFM oxide, or electrodecomprising 722 or 733 with layer 728) that may not contact the word-linecontact is disposed on the gate electrode 1012.

In some embodiments, the transistor MN associated with substrate 1001 isa metal-oxide-semiconductor field-effect transistor (MOSFET or simplyMOS transistors), fabricated on the substrate 1001. In variousembodiments of the present disclosure, the transistor may be planartransistors, nonplanar transistors, or a combination of both. Nonplanartransistors include FinFET transistors such as double-gate transistorsand tri-gate transistors, and wrap-around or all-around gate transistorssuch as nanoribbon and nanowire transistors. In an embodiment, thetransistor is a tri-gate transistor.

In some embodiments, a voltage VDS is applied between the bit-line (BL)1030 and the source-line (SL) 1040 and a word-line 1050 is energizedabove a threshold voltage, V_(TH) on the transistor. In someembodiments, an electron current (spin hall current) flows through thespin orbit torque electrode 722/733 (or electrode comprising 222/728,where layer 728 is an AFM oxide, or electrode comprising 722 or 733 withlayer 728) and causes a spin diffusion current to flow toward the MTJmemory device 200/300/400. The spin diffusion current exerts a torque onthe magnetization of the free magnet 721 aa/821 aa of MTJ721/821/831/841/851/861/871.

In some embodiments, by applying a voltage VDS between bit-line 1030 andsource-line 1040, current can flow through the MTJ memory device ofFIGS. 7-8. In some embodiments, a voltage VDS that is equal to orgreater than the threshold voltage VTS is enough to generate spinpolarized current through the MTJ 721/821/831/841/851/861/871. In someembodiments, the spin transfer torque current flowing through the MTJ221/321/421 also imparts torque to the free magnet 421 a/721 aa//821 aaadding to the torque from the spin diffusion current. In someembodiments, the combined effect of the spin transfer torque and thespin diffusion torque can switch the magnetization of the free magnet421 a/721 aa//821 aa. In some embodiments, by reversing the polarity ofthe voltage V_(DS), and applying a voltage that meets or exceeds athreshold voltage, the direction of magnetization of the free magnet 421a/721 aa//821 aa is switched back to a previous configuration.

In some embodiments, by applying a voltage between a bit-line 1030 andsource-line 1030, and by applying a voltage above a threshold voltage,V_(TH) on the word-line 1050 of the transistor, the MTJ memory deviceFIGS. 7-8 can undergo magnetization switching without the need for anadditional voltage source (e.g. a second transistor). In someembodiments, implementing an SOT memory device FIGS. 7-8 above atransistor can increase the number of SOT memory devices FIGS. 7-8 in agiven area of a die by at least a factor of two.

In some embodiments, the underlying substrate 1001 represents a surfaceused to manufacture integrated circuits. In some embodiments, thesubstrate 1001 includes a suitable semiconductor material such as butnot limited to, single crystal silicon, polycrystalline silicon andsilicon on insulator (SOI). In another embodiment, the substrate 1001includes other semiconductor materials such as germanium, silicongermanium, or a suitable group III-V or group III-N compound. Thesubstrate 1001 may also include semiconductor materials, metals,dopants, and other materials commonly found in semiconductor substrates.

In some embodiments, the transistor includes a gate stack formed of atleast two layers, a gate dielectric layer 1010 and a gate electrodelayer 1012. The gate dielectric layer 1010 may include one layer or astack of layers. The one or more layers may include silicon oxide,silicon dioxide (Sift) and/or a high-k dielectric material. The high-kdielectric material may include elements such as hafnium, silicon,oxygen, titanium, tantalum, lanthanum, aluminum, zirconium, barium,strontium, yttrium, lead, scandium, niobium, and zinc. Examples ofhigh-k materials that may be used in the gate dielectric layer include,but are not limited to, hafnium oxide, hafnium silicon oxide, lanthanumoxide, lanthanum aluminum oxide, zirconium oxide, zirconium siliconoxide, tantalum oxide, titanium oxide, barium strontium titanium oxide,barium titanium oxide, strontium titanium oxide, yttrium oxide, aluminumoxide, lead scandium tantalum oxide, and lead zinc niobate. In someembodiments, an annealing process may be carried out on the gatedielectric layer 1010 to improve its quality when a high-k material isused.

The gate electrode layer 1012 of the transistor 700 is formed on thegate dielectric layer 1010 and may comprise of at least one P-typework-function metal or N-type work-function metal, depending on whetherthe transistor is to be a PMOS or an NMOS transistor. In someembodiments, the gate electrode layer 1012 may comprise of a stack oftwo or more metal layers, where one or more metal layers arework-function metal layers and at least one metal layer is a conductivefill layer.

For a PMOS transistor, metals that may be used for the gate electrodelayer 1012 include, but are not limited to, ruthenium, palladium,platinum, cobalt, nickel, and conductive metal oxides, e.g., rutheniumoxide. A P-type metal layer will enable the formation of a PMOS gateelectrode layer 1012 with a work-function that is between about 4.9 eVand about 5.2 eV. For an NMOS transistor, metals that may be used forthe gate electrode layer 1012 include, but are not limited to, hafnium,zirconium, titanium, tantalum, aluminum, alloys of these metals, andcarbides of these metals such as hafnium carbide, zirconium carbide,titanium carbide, tantalum carbide, and aluminum carbide. An N-typemetal layer will enable the formation of an NMOS gate electrode layer1012 with a work-function that is between about 3.9 eV and about 4.2 eV.

In some embodiments, the gate electrode layer 1012 may comprise a“U”-shaped structure that includes a bottom portion substantiallyparallel to the surface of the substrate and two sidewall portions thatare substantially perpendicular to the top surface of the substrate. Inanother embodiment, at least one of the metal layers that form the gateelectrode layer 1012 may simply be a planar layer that is substantiallyparallel to the top surface of the substrate and does not includesidewall portions substantially perpendicular to the top surface of thesubstrate. In some embodiments of the present disclosure, the gateelectrode layer 1012 may comprise of a combination of U-shapedstructures and planar, non-U-shaped structures. For example, the gateelectrode layer 1012 may comprise of one or more U-shaped metal layersformed atop one or more planar, non-U-shaped layers.

In some embodiments, a pair of gate dielectric layer 1010 may be formedon opposing sides of the gate stack that bracket the gate stack. Thegate dielectric layer 710 may be formed from a material such as siliconnitride, silicon oxide, silicon carbide, silicon nitride doped withcarbon, and silicon oxynitride. Processes for forming sidewall spacersare well known in the art and generally include deposition and etchingprocess operations. In some embodiments, a plurality of spacer pairs maybe used, for instance, two pairs, three pairs, or four pairs of sidewallspacers may be formed on opposing sides of the gate stack.

In some embodiments, source region 1002 and drain region 1004 are formedwithin the substrate adjacent to the gate stack of the transistor. Thesource region 1002 and drain region 1004 are generally formed usingeither an implantation/diffusion process or an etching/depositionprocess. In the former process, dopants such as boron, aluminum,antimony, phosphorous, or arsenic may be ion-implanted into thesubstrate to form the source region 1002 and drain region 1004. Anannealing process that activates the dopants and causes them to diffusefurther into the substrate typically follows the ion implantationprocess. In the latter process, the substrate may first be etched toform recesses at the locations of the source and drain regions. Anepitaxial deposition process may then be carried out to fill therecesses with material that is used to fabricate the source region 1002and drain region 1004. In some embodiments, the source region 1002 anddrain region 1004 may be fabricated using a silicon alloy such assilicon germanium or silicon carbide. In some embodiments, theepitaxially deposited silicon alloy may be doped in-situ with dopantssuch as boron, arsenic, or phosphorous. In some embodiments, the sourceregion 1002 and drain region 1004 may be formed using one or morealternate semiconductor materials such as germanium or a suitable groupIII-V compound. In some embodiments, one or more layers of metal and/ormetal alloys may be used to form the source region 1002 and drain region1004.

In some embodiments, the gate contact 1014 and drain contact 1018 of thetransistor 700 are disposed in a first dielectric layer 1020 disposedabove the substrate 1001. In some embodiments, the spin orbit torqueelectrode 722/733 (or electrode comprising 222/728, where layer 728 isan AFM oxide, or electrode comprising 722 or 733 with layer 728) isdisposed in a second dielectric layer 1022 disposed on the firstdielectric layer 1020. In some embodiments, a third dielectric layer1024 is disposed on the second dielectric layer 1022. In someembodiments, a fourth dielectric layer 1026 is disposed on the thirddielectric layer 1024. In some embodiments, a source contact 1016 ispartially disposed in the fourth dielectric layer 1026, partiallydisposed in the third dielectric layer 1024, partially disposed in thesecond dielectric layer 1022 and partially disposed on the firstdielectric layer 1020. In some embodiments, the spin orbit torqueelectrode contact is disposed in the third dielectric layer 1024 on thespin orbit torque electrode 722/733 (or electrode comprising 222/728,where layer 728 is an AFM oxide, or electrode comprising 722 or 733 withlayer 728). In some embodiments, the conductive interconnect structuresuch as conductive interconnect structure 1008A/B disposed in the fourthdielectric layer 1026.

The gate contract 1014 is formed in poly region; drain contract 1018 isformed in active, poly, and Metal 0 (M0); SOT or SHE electrode 222 isformed in Via 0-1 layer; MTJ MTJ 721/821/831/841/851/861/871 is formedin Metal 1 (M1) and Via 1-2; contract 708 a is formed in Metal 2 (M2)and Via 2-3; and conductor 1008B is formed in Metal 3 (M3).

In some embodiments, the magnetic junction (e.g., MTJ721/821/831/841/851/861/871 or spin valve) is formed in the metal 3 (M3)region. In some embodiments, the free magnet layer 421 a of the magneticjunction 721/821/831/841/851/861/871 couples to electrode 722/733 (orelectrode comprising 222/728, where layer 728 is an AFM oxide, orelectrode comprising 722 or 733 with layer 728). In some embodiments,the fixed magnet layer 421 c/821 cc of magnetic junction721/821/831/841/851/861/871 couples to the bit-line (BL) via electrode722/733 (or electrode comprising 222/728, where layer 728 is an AFMoxide, or electrode comprising 722 or 733 with layer 728) through Via3-4 (e.g., via connecting metal 4 region to metal 4 (M4)). In thisexample embodiments, the bit-line is formed on M4.

In some embodiments, an n-type transistor MN is formed in the frontendof the die while the electrode 722/733 (or electrode comprising 222/728,where layer 728 is an AFM oxide, or electrode comprising 722 or 733 withlayer 728) is located in the backend of the die. Here, the term“backend” generally refers to a section of a die which is opposite of a“frontend” and where an IC (integrated circuit) package couples to ICdie bumps. For example, high level metal layers (e.g., metal layer 6 andabove in a ten-metal stack die) and corresponding vias that are closerto a die package are considered part of the backend of the die.Conversely, the term “frontend” generally refers to a section of the diethat includes the active region (e.g., where transistors are fabricated)and low-level metal layers and corresponding vias that are closer to theactive region (e.g., metal layer 5 and below in the ten-metal stack dieexample). In some embodiments, the electrode 722/733 (or electrodecomprising 222/728, where layer 728 is an AFM oxide, or electrodecomprising 722 or 733 with layer 728) is located in the backend metallayers or via layers for example in Via 3. In some embodiments, theelectrical connectivity to the device is obtained in layers M0 and M4 orM1 and M5 or any set of two parallel interconnects. In some embodiments,the MTJ 721/821/831/841/851/861/871 is formed in metal 2 (M2) and metal1 (M1) layer region and/or Via 1-2 region. In some embodiments,electrode 722/733 (or electrode comprising 222/728, where layer 728 isan AFM oxide, or electrode comprising 722 or 733 with layer 728) isformed in the metal 1 region.

FIG. 11 illustrates a flowchart 1100 of a method for forming a device ofFIGS. 7-8, in accordance with some embodiments. While the followingblocks (or process operations) in the flowchart are arranged in acertain order, the order can be changed. In some embodiments, someblocks can be executed in parallel. At block 1101, a magnetic junctionis formed having a magnet with a first magnetization (e.g.,perpendicular magnetizations). At block 1102, an interconnect (e.g., theelectrode 722/733 (or electrode comprising 222/728, where layer 728 isan AFM oxide, or electrode comprising 722 or 733 with layer 728)) isformed adjacent to the magnetic junction. In some embodiments, theinterconnect comprises an AFM material which is doped with a dopingmaterial to increase the blocking temperature. In some embodiments, thedoping material includes one or more of: Pt, Ni, Co, or Cr.

At block 1103, a structure adjacent to the interconnect such that themagnetic junction and the structure are on opposite surfaces of theinterconnect, wherein the structure comprises a magnet with a secondmagnetization substantially different from the first magnetization.

In some embodiments, forming the magnetic junction comprises: forming astack of structures including: forming a first structure comprising amagnet with an unfixed perpendicular magnetic anisotropy (PMA) relativeto an x-y plane of a device; forming a second structure comprising oneof a dielectric or metal; and forming a third structure comprising amagnet with fixed PMA, wherein the third structure has an anisotropyaxis perpendicular to the plane of the device, and wherein the thirdstructure is adjacent to the second structure such that the secondstructure is between the first and third structures.

In some embodiments, the interconnect is adjacent to the thirdstructure. In some embodiments, the method comprises forming a fourthstructure adjacent to the interconnect such that the third and fourthstructures are on opposite surfaces of the interconnect, wherein thefourth structure comprises a magnet with in-plane magnetization relativeto the x-y plane of the device. In some embodiments, the method offorming the magnetic junction comprises: forming a fifth structurebetween the first and second structures, wherein the fifth structureincludes one or more of: Ru, Os, Hs, or Fe; or forming a sixth structurebetween the second and third structures, wherein the sixth structureincludes one or more of: Ru, Os, Hs, or Fe.

In some embodiments, the method comprises forming a seventh structurebetween the interconnect and the fourth structure, wherein the seventhstructure includes an AFM material, and wherein the interconnectcomprises a spin orbit material. In some embodiments, the AFM materialincludes one of: Ir, Pt, Mn, Pd, or Fe. In some embodiments, the AFMmaterial is a quasi-two-dimensional triangular AFM includingNi_((1-x))M_(x)Ga₂S₄, where ‘M’ includes one of: Mn, Fe, Co or Zn. Insome embodiments, forming the first or third structures comprisesforming a stack including a first material and a second materialdifferent from the first material. In some embodiments, the firstmaterial includes one of: Co, Ni, Fe, or a Heusler alloy. In someembodiments, the Heusler alloy includes one or more of Co, Cu, Fe, Ga,Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, or V. In some embodiments,the second material includes one of: Pt, Pd, Ir, Ru, or Ni. In someembodiments, the first material has a thickness in a range of 0.6 nm to2 nm, and wherein the second material has a thickness in a range of 0.1nm to 3 nm. In some embodiments, the dielectric comprises: Mg and O.

In some embodiments, forming the first or the third structures comprisesforming a super lattice including a first material and a secondmaterial, wherein the first material includes one of: Co, Ni, Fe, orHeusler alloy; and wherein the second material includes one of: Pt, Pd,Ir, Ru, or Ni. In some embodiments, forming the first or thirdstructures comprises a stack of three materials including a firstmaterial adjacent to the fourth structure, a second material adjacent tothe first material but not in contact with the fourth structure, andthird material adjacent to the second material and the second structure,wherein the first material includes one or more of: Co, Ni, Fe, orHeusler alloy, wherein the second material comprises Ru; and wherein thethird material includes one or more of Co, Ni, Fe, or Heusler alloy. Insome embodiments, the interconnect includes one or more or: β-Tantalum(β-Ta), Ta, β-Tungsten (β-W), W, Platinum (Pt), Copper (Cu) doped withelements including on of Iridium, Bismuth or elements of 3d, 4d, 5d and4f, 5f periodic groups, Ti, S, W, Mo, Se, B, Sb, Re, La, C, P, La, As,Sc, O, Bi, Ga, Al, Y, In, Ce, Pr, Nd, F, Ir, Mn, Pd, or Fe. In someembodiments, the interconnect comprises a spin orbit material whichincludes one of: a 2D material, a 3D material, an AFM material, or anAFM material doped with a doping material. In some embodiments, the 3Dmaterial is thinner than the 2D material. In some embodiments, thedoping material includes one of: Co, Fe, Ni, Mn, Ga, Fe, or Bct-Ru.

In some embodiments, forming the interconnect comprises forming a stackof layers, wherein one of the layer in the stack comprises an AFMmaterial. In some embodiments, the magnetic junction is one of a spinvalve or a magnetic tunneling junction (MTJ). In some embodiments, themagnet of the first structure is a paramagnet which includes one or moreof: Pt, Pd, W, Ce, Al, Li, Mg, Na, Cr, Co, Dy, O, Er, Eu, Eu, Gd, Fe,Nd, K, Pr, Sm, Tb, Tm, or V, or wherein the magnet of the firststructure is a paramagnet which comprises dopants which include one ormore of: Ce, Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb.

FIG. 12 illustrates a smart device or a computer system or a SoC(System-on-Chip) with a magnetic junction based memory having a via fordipole and exchange coupling in the SOT/AFM interconnect with higherblocking temperature, according to some embodiments of the disclosure.

For purposes of the embodiments, the transistors in various circuits andlogic blocks described here are metal oxide semiconductor (MOS)transistors or their derivatives, where the MOS transistors includedrain, source, gate, and bulk terminals. The transistors and/or the MOStransistor derivatives also include Tri-Gate and FinFET transistors,Gate All Around Cylindrical Transistors, Tunneling FET (TFET), SquareWire, or Rectangular Ribbon Transistors, ferroelectric FET (FeFETs), orother devices implementing transistor functionality like carbonnanotubes or spintronic devices. MOSFET symmetrical source and drainterminals i.e., are identical terminals and are interchangeably usedhere. A TFET device, on the other hand, has asymmetric Source and Drainterminals. Those skilled in the art will appreciate that othertransistors, for example, Bi-polar junction transistors (BJT PNP/NPN),BiCMOS, CMOS, etc., may be used without departing from the scope of thedisclosure.

FIG. 12 illustrates a block diagram of an embodiment of a mobile devicein which flat surface interface connectors could be used. In someembodiments, computing device 1600 represents a mobile computing device,such as a computing tablet, a mobile phone or smart-phone, awireless-enabled e-reader, or other wireless mobile device. It will beunderstood that certain components are shown generally, and not allcomponents of such a device are shown in computing device 1600.

In some embodiments, computing device 1600 includes first processor 1610with one or more devices according to any one of devices of FIGS. 7-8,according to some embodiments discussed. Other blocks of the computingdevice 1600 may also include one or more devices according to any one ofdevices of FIGS. 7-8, according to some embodiments. The variousembodiments of the present disclosure may also comprise a networkinterface within 1670 such as a wireless interface so that a systemembodiment may be incorporated into a wireless device, for example, cellphone or personal digital assistant.

In some embodiments, processor 1610 (and/or processor 1690) can includeone or more physical devices, such as microprocessors, applicationprocessors, microcontrollers, programmable logic devices, or otherprocessing means. The processing operations performed by processor 1610include the execution of an operating platform or operating system onwhich applications and/or device functions are executed. The processingoperations include operations related to I/O (input/output) with a humanuser or with other devices, operations related to power management,and/or operations related to connecting the computing device 1600 toanother device. The processing operations may also include operationsrelated to audio I/O and/or display I/O.

In some embodiments, computing device 1600 includes audio subsystem1620, which represents hardware (e.g., audio hardware and audiocircuits) and software (e.g., drivers, codecs) components associatedwith providing audio functions to the computing device. Audio functionscan include speaker and/or headphone output, as well as microphoneinput. Devices for such functions can be integrated into computingdevice 1600, or connected to the computing device 1600. In oneembodiment, a user interacts with the computing device 1600 by providingaudio commands that are received and processed by processor 1610.

In some embodiments, computing device 1600 comprises display subsystem1630. Display subsystem 1630 represents hardware (e.g., display devices)and software (e.g., drivers) components that provide a visual and/ortactile display for a user to interact with the computing device 1600.Display subsystem 1630 includes display interface 1632, which includesthe particular screen or hardware device used to provide a display to auser. In one embodiment, display interface 1632 includes logic separatefrom processor 1610 to perform at least some processing related to thedisplay. In one embodiment, display subsystem 1630 includes a touchscreen (or touch pad) device that provides both output and input to auser.

In some embodiments, computing device 1600 comprises I/O controller1640. I/O controller 1640 represents hardware devices and softwarecomponents related to interaction with a user. I/O controller 1640 isoperable to manage hardware that is part of audio subsystem 1620 and/ordisplay subsystem 1630. Additionally, I/O controller 1640 illustrates aconnection point for additional devices that connect to computing device1600 through which a user might interact with the system. For example,devices that can be attached to the computing device 1600 might includemicrophone devices, speaker or stereo systems, video systems or otherdisplay devices, keyboard or keypad devices, or other I/O devices foruse with specific applications such as card readers or other devices.

As mentioned above, I/O controller 1640 can interact with audiosubsystem 1620 and/or display subsystem 1630. For example, input througha microphone or other audio device can provide input or commands for oneor more applications or functions of the computing device 1600.Additionally, audio output can be provided instead of, or in addition todisplay output. In another example, if display subsystem 1630 includes atouch screen, the display device also acts as an input device, which canbe at least partially managed by I/O controller 1640. There can also beadditional buttons or switches on the computing device 1600 to provideI/O functions managed by I/O controller 1640.

In some embodiments, I/O controller 1640 manages devices such asaccelerometers, cameras, light sensors or other environmental sensors,or other hardware that can be included in the computing device 1600. Theinput can be part of direct user interaction, as well as providingenvironmental input to the system to influence its operations (such asfiltering for noise, adjusting displays for brightness detection,applying a flash for a camera, or other features).

In some embodiments, computing device 1600 includes power management1650 that manages battery power usage, charging of the battery, andfeatures related to power saving operation. Memory subsystem 1660includes memory devices for storing information in computing device1600. Memory can include nonvolatile (state does not change if power tothe memory device is interrupted) and/or volatile (state isindeterminate if power to the memory device is interrupted) memorydevices. Memory subsystem 1660 can store application data, user data,music, photos, documents, or other data, as well as system data (whetherlong-term or temporary) related to the execution of the applications andfunctions of the computing device 1600.

Elements of embodiments are also provided as a machine-readable medium(e.g., memory 1660) for storing the computer-executable instructions(e.g., instructions to implement any other processes discussed herein).The machine-readable medium (e.g., memory 1660) may include, but is notlimited to, flash memory, optical disks, CD-ROMs, DVD ROMs, RAMs,EPROMs, EEPROMs, magnetic or optical cards, phase change memory (PCM),or other types of machine-readable media suitable for storing electronicor computer-executable instructions. For example, embodiments of thedisclosure may be downloaded as a computer program (e.g., BIOS) whichmay be transferred from a remote computer (e.g., a server) to arequesting computer (e.g., a client) by way of data signals via acommunication link (e.g., a modem or network connection).

In some embodiments, computing device 1600 comprises connectivity 1670.Connectivity 1670 includes hardware devices (e.g., wireless and/or wiredconnectors and communication hardware) and software components (e.g.,drivers, protocol stacks) to enable the computing device 1600 tocommunicate with external devices. The computing device 1600 could beseparate devices, such as other computing devices, wireless accesspoints or base stations, as well as peripherals such as headsets,printers, or other devices.

Connectivity 1670 can include multiple different types of connectivity.To generalize, the computing device 1600 is illustrated with cellularconnectivity 1672 and wireless connectivity 1674. Cellular connectivity1672 refers generally to cellular network connectivity provided bywireless carriers, such as provided via GSM (global system for mobilecommunications) or variations or derivatives, CDMA (code divisionmultiple access) or variations or derivatives, TDM (time divisionmultiplexing) or variations or derivatives, or other cellular servicestandards. Wireless connectivity (or wireless interface) 1674 refers towireless connectivity that is not cellular, and can include personalarea networks (such as Bluetooth, Near Field, etc.), local area networks(such as Wi-Fi), and/or wide area networks (such as WiMax), or otherwireless communication.

In some embodiments, computing device 1600 comprises peripheralconnections 1680. Peripheral connections 1680 include hardwareinterfaces and connectors, as well as software components (e.g.,drivers, protocol stacks) to make peripheral connections. It will beunderstood that the computing device 1600 could both be a peripheraldevice (“to” 1682) to other computing devices, as well as haveperipheral devices (“from” 1684) connected to it. The computing device1600 commonly has a “docking” connector to connect to other computingdevices for purposes such as managing (e.g., downloading and/oruploading, changing, synchronizing) content on computing device 1600.Additionally, a docking connector can allow computing device 1600 toconnect to certain peripherals that allow the computing device 1600 tocontrol content output, for example, to audiovisual or other systems.

In addition to a proprietary docking connector or other proprietaryconnection hardware, the computing device 1600 can make peripheralconnections 1680 via common or standards-based connectors. Common typescan include a Universal Serial Bus (USB) connector (which can includeany of a number of different hardware interfaces), DisplayPort includingMiniDisplayPort (MDP), High Definition Multimedia Interface (HDMI),Firewire, or other types.

Reference in the specification to “an embodiment,” “one embodiment,”“some embodiments,” or “other embodiments” means that a particularfeature, structure, or characteristic described in connection with theembodiments is included in at least some embodiments, but notnecessarily all embodiments. The various appearances of “an embodiment,”“one embodiment,” or “some embodiments” are not necessarily allreferring to the same embodiments. If the specification states acomponent, feature, structure, or characteristic “may,” “might,” or“could” be included, that particular component, feature, structure, orcharacteristic is not required to be included. If the specification orclaim refers to “a” or “an” element, that does not mean there is onlyone of the elements. If the specification or claims refer to “anadditional” element, that does not preclude there being more than one ofthe additional element.

Furthermore, the particular features, structures, functions, orcharacteristics may be combined in any suitable manner in one or moreembodiments. For example, a first embodiment may be combined with asecond embodiment anywhere the particular features, structures,functions, or characteristics associated with the two embodiments arenot mutually exclusive.

While the disclosure has been described in conjunction with specificembodiments thereof, many alternatives, modifications and variations ofsuch embodiments will be apparent to those of ordinary skill in the artin light of the foregoing description. The embodiments of the disclosureare intended to embrace all such alternatives, modifications, andvariations as to fall within the broad scope of the appended claims.

In addition, well known power/ground connections to integrated circuit(IC) chips and other components may or may not be shown within thepresented figures, for simplicity of illustration and discussion, and soas not to obscure the disclosure. Further, arrangements may be shown inblock diagram form in order to avoid obscuring the disclosure, and alsoin view of the fact that specifics with respect to implementation ofsuch block diagram arrangements are highly dependent upon the platformwithin which the present disclosure is to be implemented (i.e., suchspecifics should be well within purview of one skilled in the art).Where specific details (e.g., circuits) are set forth in order todescribe example embodiments of the disclosure, it should be apparent toone skilled in the art that the disclosure can be practiced without, orwith variation of, these specific details. The description is thus to beregarded as illustrative instead of limiting.

An abstract is provided that will allow the reader to ascertain thenature and gist of the technical disclosure. The abstract is submittedwith the understanding that it will not be used to limit the scope ormeaning of the claims. The following claims are hereby incorporated intothe detailed description, with each claim standing on its own as aseparate embodiment.

We claim:
 1. An apparatus comprising: a magnetic junction coupled to afirst circuit node, the magnetic junction including: a stack comprising:a first structure comprising a magnet with an unfixed perpendicularmagnetic anisotropy (PMA) relative to an x-y plane within the stack; asecond structure comprising a dielectric or metal; and a third structurecomprising a magnet with fixed PMA, wherein the third structure has ananisotropy axis perpendicular to the x-y plane, and wherein the secondstructure is between the first and third structures; and a spin orbitcoupling (SOC) interconnect coupling a second circuit node to a thirdcircuit node, and adjacent to the first structure, wherein theinterconnect comprises an antiferromagnetic (AFM) material that is dopedwith one or more of O, N Ta, Pt, W, Mo, Co, Ni, Fe, Mn, Ga, or Ru. 2.The apparatus of claim 1, wherein the AFM material is doped with one ormore of: O or N.
 3. The apparatus of claim 1, comprising a fourthstructure adjacent to the SOC interconnect, wherein the first and fourthstructures are on opposite surfaces of the SOC interconnect, wherein thefourth structure comprises a magnet with in-plane magnetization relativeto the x-y plane.
 4. The apparatus of claim 1, wherein the magneticjunction comprises: a fifth structure between the first and secondstructures, wherein the fifth structure includes one or more of: Ru, Os,Hs, or Fe; or a sixth structure between the second and third structures,wherein the sixth structure includes one or more of: Ru, Os, Hs, or Fe.5. The apparatus of claim 3, comprises: a seventh structure between theSOC interconnect and the fourth structure, wherein the seventh structureincludes a second AFM material.
 6. The apparatus of claim 5, wherein atleast one of the AFM material or the second AFM material includes oneof: Jr, Pt, Mn, Pd, or Fe.
 7. The apparatus of claim 5, wherein at leastone of the AFM material or the second AFM material is aquasi-two-dimensional triangular AFM material includingNi_((i-x))M_(x)Ga₂S₄, where ‘M’ includes one of: Mn, Fe, Co or Zn. 8.The apparatus of claim 1, wherein: the first or third structurescomprises a stack including a first material and a second materialdifferent from the first material; the first material includes one of:Co, Ni, Fe, or a Heusler alloy; the Heusler alloy includes one or moreof Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, or V; thesecond material includes one of: Pt, Pd, Jr, Ru, or Ni; and wherein thefirst material has a thickness in a range of 0.6 nm to 2 nm, and whereinthe second material has a thickness in a range of 0.1 nm to 3 nm.
 9. Theapparatus of claim 1, wherein the dielectric comprises: Mg and O. 10.The apparatus of claim 1, wherein the first or the third structurescomprises a super lattice including a first material and a secondmaterial, wherein the first material includes one of: Co, Ni, Fe, orHeusler alloy; and wherein the second material includes one of: Pt, Pd,Jr, Ru, or Ni.
 11. The apparatus of claim 3, wherein the first or thirdstructures comprises a stack of three materials including a firstmaterial adjacent to the fourth structure, a second material adjacent tothe first material but not in contact with the fourth structure, andthird material adjacent to the second material and the second structure,wherein the first material includes one or more of: Co, Ni, Fe, orHeusler alloy, wherein the second material comprises Ru; and wherein thethird material includes one or more of Co, Ni, Fe, or Heusler alloy. 12.The apparatus of claim 1, wherein the SOC interconnect includes one ormore of: β-Tantalum (β-Ta), Ta, β-Tungsten (β-W), W, Platinum (Pt),Copper (Cu) doped with elements including one or more of Iridium,Bismuth or elements of 3d, 4d, 5d and 4f, 5f periodic groups, Ti, S, W,Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In, Ce, Pr,Nd, F, Ir, Mn, Pd, or Fe.
 13. The apparatus of claim 1, wherein the SOCinterconnect comprises a stack of layers, wherein one of the layers inthe stack comprises the AFM material.
 14. The apparatus of claim 1,wherein the magnetic junction is one of a spin valve or a magnetictunneling junction (MTJ).
 15. The apparatus of claim 1, wherein themagnet of the first structure is a paramagnet that includes one or moreof: Pt, Pd, W, Ce, Al, Li, Mg, Na, Cr, Co, Dy, O, Er, Eu, Eu, Gd, Fe,Nd, K, Pr, Sm, Tb, Tm, or V, or wherein the magnet of the firststructure is a paramagnet which that comprises dopants which include oneor more of: Ce, Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, orYb.
 16. A system comprising: a memory; a processor coupled to thememory, the processor having a magnetic memory, which comprises: amagnetic junction coupled to a first circuit node, the magnetic junctionhaving a magnet with a first magnetization; a spin orbit coupling (SOC)interconnect coupling a second circuit node to a third circuit node, andadjacent to the magnetic junction, wherein the SOC interconnectcomprises an antiferromagnetic (AFM) material that is doped with one ormore of O, N Ta, Pt, W, Mo, Co, Ni, Fe, Mn, Ga, or Ru; and a structureadjacent to the SOC interconnect, wherein the magnetic junction and thestructure are on opposite surfaces of the interconnect, wherein thestructure comprises a magnet with a second magnetization substantiallydifferent from the first magnetization; and a wireless interface toallow the processor to communicate with another device.
 17. The systemof claim 16, wherein the AFM material is doped with one or more of: O,or N.